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University  of  California. 


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THE  TELEPHONE 
THE  MICROPHONE  AND  THE  PHONOGRAPH 


THE  TELEPHONE 

THE  MICROPHONE  AND  THE  PHONOGRAPH 


BY  COUNT  DU  MONCEL 

'  i 
MEMBRE   DE   L'lNSTITUT 


AUTHORIZED   TRANSLATION 
WITH  ADDITIONS  AND  CORRECTIONS  BY  THE  AUTHOR 


WITH    70    ILLUSTRATIONS    ON    WOOD 


LIIU4A  U  : 


UNIVERSITY 

< 


NEW    YORK 

HARPER    &    BROTHERS,    PUBLISHERS 

FRANKLIN     SQUARE 

1879 


/313S 


CONTENTS. 


Page 

History  of  the  Telephone 11 


MUSICAL  TELEPHONES. 

Reiss's  Telephone. .. 18 

Wray's  Telephone 21 

Electric  Harmonica 23 

Gray's  Telephone „ 26 

Pollard  and  Garnier's  Singing  Condenser 29 

SPEAKING  -TELEPHONES. 

String  Telephones 33 

Bell's  Electric  Telephone 36 

Gray's  Share  in  Invention  of  Telephone 56 

FUNDAMENTAL  PRINCIPLES  OF  BELL  TELEPHONE. 

Explanation  of  Principles 60 

ORDINARY  ARRANGEMENT  OF  BELL  TELEPHONE. 

Description  and  Illustrations „. 63 

BATTERY  TELEPHONES. 

Edison's  Telephone. , 72 

Edison's  Chemical  Telephone 76 

Navez's  Telephones 78 

Pollard  and  Garnier's  Telephones 81 

Hellesen's  Telephone 83 


6  CONTENTS. 

Page 

Thomson  and  Houston's  Telephone 84 

Telephones  with  Liquid  Senders 86 

Telephones  with  Voltaic  Arcs 88 

Mercury  Telephones 90 

Friction  Telephones 93 

MODIFICATION   OF  BELL  TELEPHONES. 

Telephones  with  several  Diaphragms 94 

Gray's  System 95 

Phelps's  System 96 

Cox  Walker's  System 98 

Trouve's  System 99 

Demoget's  System 101 

M'Tighe's  Telephone 101 

Modifications  of  Telephonic  Organs 102 

Righi's  System 103 

Ader's  System 105 

Jorgenson's  System 106 

EXPERIMENTS  WITH  THE  TELEPHONE. 

On  the  Effects  of  Voltaic  and  Induced  Currents 107 

On  the  Effects  of  different  Telephonic  Organs Ill 

Edison's  Experiments 112 

Canestrelli's  Experiments 114 

Hughes's  and  Roy's  Experiments 114 

Breguet's  Experiments 119 

Luvini's  Experiments , 119 

Warwick's  Experiments 121 

Experiments  on  the  Effects  of  Mechanical  Shocks 123 

Des  Portes's  Experiments 123 

Thompson's  Experiments 125 

Theory  of  the  Telephone 126 


CONTENTS.  7 

Page 

Nature  of  Vibrations 126 

Action  of  Diaphragm 129 

Action  of  Magnet 131 

Action  6f  Currents 133 

Wiesendanger's  Thermophone 134 

OTHER  EXPERIMENTS  WITH  THE  TELEPHONE. 

D'Arsonval's  Experiments 136 

Eick's  Experiments 138 

Demoget's  Experiments 138 

Sensitiveness  of  Telephone. .  , 140 

Hellesen's  Experiments 141 

Zetsche's  Experiments v , 142 

THE  MICROPHONE. 

History  of  the  Microphone 143 

Different  Systems 146 

Hughes's  Microphone 147 

Gaiffe's  System 148 

Carette's  System 149 

Ducretet's  System. 150 

Ducretet's  Speaker 151 

Boudet's  Speaker 152 

Gaiffe's  Thermoscope 154 

Blyth's  System 155 

Microphone  as  a  Speaking  Instrument 156 

Hughes's  System 157 

Other  Arrangements  of  Microphones 159 

Varey's  and  Trouve's  Microphones 161 

Lippens's  Microphone 162 

Hughes's  Experiments 164 

Hughes's  Theory...                                                                                 .  166 


8  CONTENTS. 

Page 

Microphone  used  as  Thermoscope 169 

Edison's  Thermoscope 170 

Experiments  in  London 170 

Experiment  at  Bellinzona 172 

APPLICATIONS  OF  THE  MICROPHONE. 

Its  Application  to  Scientific  Research 175 

Application  to  Telephonic  Relays 177 

Application  to  Surgery. 179 

Various  Applications 182 

EXTERNAL  INFLUENCE  ON  TELEPHONIC  TRANSMISSIONS. 

Disturbing  Influences 183 

Confusion  of  Circuits 185 

Induced  Reactions 187 

Mr.  Preece's  Suggestions 188 

Effects  of  Heat  and  Moisture 191 

ESTABLISHMENT  OF  TELEPHONE  STATION. 

Pollard  and  Garnier's  System 193 

Breguet  and  Roosevelt's  System 195 

Edison's  System 199 

CALL-BELLS  AND  ALARUMS. 

Weinhold's  System 201 

Dutertre  and  Gouault's  System 203 

Puluj's  System 205 

Chiddey's  System 205 

APPLICATIONS  OF  THE   TELEPHONE. 

» 

Its  Application  to  Simultaneous  Transmissions 207 

Bell's  System 209 


CONTENTS.  9 

Page 

Lacour's  System 212 

Gray's  System 218 


VARIOUS  USES  OF  THE  TELEPHONE. 

Its  Use  in  Offices 224 

Its  Use  in  Telegraphic  Service 225 

Its  Application  to  Military  Purposes 227 

Its  Application  to  Industry 231 

Its  Application  to  Scientific  Research 231 

THE  PHONOGRAPH. 

Edison's  Patent : 235 

Description  of  Phonograph , 240 

Several  Systems 246 

Theory  of  Phonograph 250 

USES  OF  THE  PHONOGRAPH. 

Account  by  Edison 255 

Lambrigot's  System 259 

FABER'S  SPEAKING  MACHINE.. . 261 

APPENDIX. 

Perrodon's  System  of  Telephonic  Alarum 269 

Yarey's  Microphone  Speaker 270 

Fitch's  Microphone  Speaker 270 

Theory  of  Telephone 270 

Pollard's  Microphone 272 

Ader's  Electrophone 273 

Gower's  New  Telephone 273 

Transmission  of  Speech  by  Telephones  without  Diaphragm 275 

1* 


,      i{ AIM 

UNJVKU.SJTV    OK 

CALIFORNIA. 

x^ 

THE  TELEPHONE,  ETC 


HISTORY  OF  THE  TELEPHONE. 

STRICTLY  speaking,  the  telephone  is  merely  an  instrument 
adapted  for  the  transmission  of  sound  to  a  distance,  and  this 
idea  of  transmitting  sound  is  as  old  as  the  world  itself.  The 
Greeks  made  use  of  means  which  might  effect  it,  and  there  is 
no  doubt  that  these  means  were  sometimes  used  for  the  pagan 
oracles.  But  such  transmission  of  sound  was  within  some- 
what narrow  limits,  and  certainly  did  not  exceed  those  of  a 
speaking-tube.  Mr.  Preece  considers  that  the  earliest  document 
in  which  this  transmission  of  sound  to  a  distance  is  distinctly 
formulated  dates  from  1667  :  he  refers  to  a  paper  by  one  Rob- 
ert Hooke,  who  writes  to  this  effect :  "  It  is  not  impossible  to 
hear  a  whisper  at  a  furlong's  distance,  it  having  been  already 
done ;  and  perhaps  the  nature  of  the  thing  would  not  make  it 
more  impossible,  though  that  furlong  should  be  ten  times  mul- 
tiply'd.  And  though  some  famous  authors  have  affirm'd  it  im- 
possible to  hear  through  the  thinnest  plate  of  Muscovy  glass; 
yet  I  know  a  way  by  which  'tis  easie  enough  to  hear  one 
speak  through  a  wall  a  yard  thick.  It  has  not  yet  been  thor- 
oughly examin'd  how  far  otacousticons  may  be  improv'd,  nor 
what  other  wayes  there  may  be  of  quickning  our  hearing,  or 
conveying  sound  through  other  bodies  than  the  air;  for  that 
that  is  not  the  only  medium,  I  can  assure  the  reader  that  I 
have,  by  the  help  of  a  distended  wire,  propagated  the  sound  to 
a  very  considerable  distance  in  an  instant,  or  with  as  seemingly 


12  THE    TELEPHONE. 

quick  a  motion  as  that  of  light,  at  least  incomparably  quicker 
than  that  which  at  the  same  time  was  propagated  through  the 
air;  and  this  not  only  in  a  straight  line  or  direct,  but  in  one 
bended  in  many  angles." 

This  plan  for  the  transmission  of  sound  is  the  principle  of 
the  string  telephones  which  have  attracted  attention  for  some 
years,  and  it  remained  in  the  stage  of  simple  experiment  until 
1819,  when  Sir  Charles  Wheatstone  applied  it  to  his  magic 
lyre.  In  this  instrument  sounds  were  transmitted  through  a 
long  strip  of  deal,  with  one  end  in  connection  with  a  sounding- 
board  :  one  step  more  led  to  the  use  of  the  membrane  em- 
ployed in  string  telephones.  It  would  be  difficult  to  say  with 
whom  this  idea  originated,  since  it  is  claimed,  as  if  beyond 
dispute,  by  several  telephone-makers.  If  we  may  believe  some 
travellers,  it  has  long  been  used  in  Spain  for  the  correspond- 
ence of  lovers.  However  this  may  be,  it  was  not  to  be  found 
among  the  scientific  appliances  of  some  years  ago,  and  it  was 
even  supposed  by  many  persons  that  the  cord  consisted  of  an 
acoustic  tube  of  slender  diameter.  Although  the  instrument 
has  become  a  child's  toy,  it  has  great  scientific  importance, 
for  it  proves  that  vibrations  capable  of  reproducing  speech 
may  be  extremely  minute,  since  they  can  be  mechanically 
transmitted  more  than  a  hundred  yards. 

From  the  telegraphic  point  of  view,  however,  the  problem 
of  transmitting  sounds  to  a  distance  was  far  from  being  solved 
in  this  way,  and  the  idea  of  applying  electricity  to  this  mode 
of  transmission  naturally  arose  as  soon  as  the  wonderful  effects 
of  electric  telegraphy  were  observed,  that  is,  in  the  years  sub- 
sequent to  1839.  A  surprising  discovery  made  in  America  by 
Mr.  Page,  in  1837,  and  afterward  investigated  by  MM.  Wert- 
heim,  De  la  Rive,  and  others,  must  also  have  led  up  to  it ;  for 
it  was  observed  that  a  magnetic  bar  could  emit  sounds  when 
rapidly  magnetized  and  demagnetized ;  and  these  sounds  cor- 
responded with  the  number  of  currents  which  produced  them. 


ELECTRIC    TRANSMISSION    OF    SOUND.  13 

Again,  the  electric  vibrators  devised  by  MM.  Macaulay,  Wagner, 
Neef,  etc.,  and  adapted  to  produce  musical  sounds,  between 
1847-1852,  by  MM.  Frornent  and  Petrina,  showed  that  the 
problem  of  transmitting  sounds  to  a  distance  was  not  insolu- 
ble. Yet,  up  to  1854,  no  one  had  ventured  to  admit  the  pos- 
sibility of  transmitting  speech  by  electricity;  and  when  M. 
Charles  Bourseul  published,  in  that  year,  a  paper  on  the  elec- 
tric transmission  of  speech,  the  idea  was  regarded  as  a  fanciful 
dream.  I  confess  that  I  myself  thought  it  incredible ;  and  when 
I  produced  the  paper  in  the  first  edition  of  my  account  of  the 
applications  of  electricity,  published  in  1854, 1  felt  bound  to 
add  that  the  scheme  seemed  more  than  doubtful.  Yet,  as  the 
paper  was  thoughtfully  written,  I  had  no  hesitation  in  publish- 
ing it,  affixing  the  signature  of  CH.  B.  Events  justified  this 
daring  idea ;  and  although  it  did  not  include  the  only  principle 
which  could  lead  to  the  reproduction  of  articulate  sounds,  yet 
it  was  the  germ  of  the  fertile  invention  which  has  made  the 
names  of  Graham  Bell  and  Elisha  Gray  famous.  For  this  rea- 
son I  will  again  quote  M.  Charles  Bourseul's  paper. 

"After  the  telegraphic  marvels  which  can  reproduce  at  a 
distance  handwritings,  or  even  more  or  less  complicated  draw- 
ings, it  may  appear  impossible  to  penetrate  farther  into  the 
region  of  the  marvellous.  Yet  we  will  try  to  advance  a  few 
steps  farther.  I  haye,  for  example,  asked  myself  whether 
speech  itself  may  not  be  transmitted  by  electricity — in  a  word, 
if  what  is  spoken  in  Vienna  may  not  be  heard  in  Paris.  The 
thing  is  practicable  in  this  way: 

"  We  know  that  sounds  are  made  by  vibrations,  and  are 
adapted  to  the  ear  by  the  same  vibrations  which  are  reproduced 
by  the  intervening  medium.  But  the  intensity  of  the  vibra- 
tions diminishes  very  rapidly  with  the  distance :  so  that  it  is, 
even  with  the  aid  of  speaking-tubes  and  trumpets,  impossible 
to  exceed  somewhat  narrow  limits.  Suppose  that  a  man  speaks 
near  a  movable  disk,  sufficiently  flexible  to  lose  none  of  the 


14  THE    TELEPHONE. 

vibrations  of  the  voice,  that  this  disk  alternately  makes  and 
breaks  the  currents  from  a  battery :  you  may  have  at  a  dis- 
tance another  disk,  which  will  simultaneously  execute  the  same 
vibrations. 

"  It  is  true  that  the  intensity  of  the  sounds  produced  will  be 
variable  at  the  point  of  departure,  at  which  the  disk  vibrates 
by  means  of  the  voice,  and  constant  at  the  point  of  arrival, 
where  it  vibrates  by  means  of  electricity;  but  it  has  been 
shown  that  this  does  not  change  the  sounds.  It  is,  moreover, 
evident  that  the  sounds  will  be  reproduced  at  the  same  pitch. 

"  The  present  state  of  acoustic  science  does  not  permit  us  to 
declare  a  priori  if  this  will  be  precisely  the  case  with  syllables 
uttered  by  the  human  voice.  The  mode  in  which  these  sylla- 
bles are  produced  has  not  yet  been  sufficiently  investigated.  It 
is  true  that  we  know  that  some  are  uttered  by  the  teeth,  others 
by  the  lips,  and  so  on ;  but  this  is  all 

"However  this  may  be,  observe  that  the  syllables  can  only 
reproduce  upon  the  sense  of  hearing  the  vibrations  of  the  in- 
tervening medium :  reproduce  precisely  these  vibrations,  and 
you  will  reproduce  precisely  these  syllables. 

"  It  is,  at  all  events,  impossible,  in  the  present  condition  of 
science,  to  prove  the  impossibility  of  transmitting  sound  by 
electricity.  Everything  tends  to  show,  on  the  contrary,  that 
there  is  such  a  possibility.  When  the  application  of  electro- 
magnetism  to  the  transmission  of  messages  was  first  discussed, 
a  man  of  great  scientific  attainments  treated  the  idea  as  Utopi- 
an, and  yet  there  is  now  direct  communication  between  Lon- 
don and  Vienna  by  means  of  a  simple  wire.  Men  declared  it 
to  be  impossible,  but  so  it  is. 

"  It  need  not  be  said  that  numerous  applications  of  the  high- 
est importance  will  immediately  arise  from  the  transmission  of 
speech  by  electricity.  Any  one  who  is  not  deaf  and  dumb  may 
use  this  mode  of  transmission,  which  would  require  no  appa- 
ratus except  an  electric  battery,  two  vibrating  disks,  and  a 


APPLICATION    OF    ELECTRICITY.  15 

wire.  In  many  cases,  as  for  example  in  large  establishments, 
orders  might  be  transmitted  in  this  way,  although  transmission 
by  electricity  will  not  be  used  while  it  is  necessary  to  go  from 
letter  to  letter,  and  to  make  use  of  telegraphs  which  require  use 
and  apprenticeship.  However  this  may  be,  it  is  certain  that, 
in  a  more  or  less  distant  future,  speech  will  be  transmitted  by 
electricity.  /  have  made  some  experiments  in  this  direction : 
they  are  delicate,  and  demand  timo  and  patience,  but  the  ap- 
proximations obtained  promise  a  favorable  result." 

This  description  is  certainly  not  full  enough  to  enable  us  to 
discern  from  it  the  arrangement  which  would  lead  to  the  solu- 
tion of  the  problem,  and  if  the  vibrations  of  the  disk  at  the  re- 
ceiving-station were  to  follow  from  making  and  breaking  the 
current  at  the  sending-station,  under  the  influence  of  vibrations 
caused  by  the  voice,  they  would  only  produce  musical,  and  not 
articulate  sounds.  Yet  the  idea  was  magnificent,  as  Mr.  Preece 
said,  even  when  he  thought  it  impossible  to  realize  it.  Besides, 
it  is  easy  to  see  that  M.  Bourseul  himself  was  not  deceived  as 
to  the  difficulties  of  the  problem,  as  far  as  articulate  sounds  are 
concerned,  for  he  points  out,  as  we  have  seen,  the  difference 
existing  between  the  simple  vibrations  which  produce  musi- 
cal sounds,  and  the  complex  vibrations  which  cause  articulate 
sounds ;  but,  as  he  justly  said,  "  Reproduce  at  the  one  end  of 
the  line  the  vibrations  of  air  caused  at  the  other,  and  speech 
will  be  transmitted,  however  complex  the  mechanism  may  be 
by  which  it  is  effected."  We  shall  presently  see  how  the 
problem  was  solved,  and  it  is  probable  that  some  attempts  had 
already  enabled  M.  Bourseul  to  anticipate  the  solution  of  the 
question  ;  but  there  is  nothing  in  his  paper  to  show  what  were 
the  means  he  proposed,  so  that  the  discovery  of  the  electric 
transmission  of  speech  cannot  reasonably  be  ascribed  to  him, 
and  we  do  not  understand  why  we  should  be  reproached  for 
having  at  that  time  failed  to  appreciate  the  importance  of  a  dis- 
covery which  seemed  to  be  then  only  within  the  range  of  fancy. 


16  THE    TELEPHONE. 

It  was  not  until  1876  that  the  problem  of  the  electric  trans- 
mission of  speech  was  finally  solved ;  and  the  discovery  has  late- 
ly given  rise  to  an  interesting  controversy  as  to  priority  be- 
tween Mr.  Elisha  Gray,  of  Chicago,  and  Mr.  Graham  Bell,  on 
which  we  must  say  a  few  words. 

As  early  as  1874  Mr.  Elisha  Gray  was  occupied  with  a  sys- 
tem of  musical  telephone,  which  he  wished  to  apply  to  mani- 
fold telegraphic  transmissions,  and  the  investigations  which  he 
made,  in  order  to  establish  this  system  under  the  best  possible 
conditions,  gave  him  a  glimpse  of  the  possibility  of  transmit- 
ting articulate  words  by  electricity.  While  carrying  on  his  ex- 
periments on  the  telegraphic  system,  he  arranged,  in  fact,  about 
the  15th  January,  1876,  a  system  of  speaking  telephone,  and  he 
deposited  the  specification  and  drawings  in  the  American  Pat- 
ent Office,  in  the  form  of  a  caveat  or  provisional  specification. 
The  deposit  was  made  on  the  14th  February,  1876:  on  the 
very  same  day  Mr.  Graham  Bell  also  deposited,  in  the  Amer- 
ican Patent  Office,  a  request  for  a  patent  in  which  he  spoke  of 
an  instrument  of  the  same  kind,  but  with  special  application  to 
simultaneous  telegraphic  transmissions  by  means  of  a  telephon- 
ic apparatus ;  and  the  few  words  which  could,  in  this  specifica- 
tion, refer  to  a  telephone  with  articulate  sounds,  applied  to  an 
instrument  which,  by  Mr.  Bell's  own  admission,  had  not  pro- 
duced any  satisfactory  results.  In  Mr.  Gray's  caveat,  on  the 
contrary,  the  application  of  the  instrument  to  the  electric  trans- 
mission of  speech  alone  is  indicated,  the  description  of  the  sys- 
tem is  complete,  and  the  drawings  which  accompany  it  are  so 
exact  that  a  telephone  made  from  them  would  work  perfectly : 
this  was  proved  by  Mr.  Gray  himself,  when,  some  time  after- 
ward, he  finished  his  instruments,  which  differed  in  no  respect 
from  the  one  described  in  Mr.  Bell's  statement  as  worked  by  a 
battery.  On  these  grounds  Mr.  Elisha  Gray  would  certainly 
have  obtained  the  patent,  if  the  expiration  of  his  caveat  had 
not  been  the  result  of  an  omission  of  form  in  the  Patent  Office, 


17 

which,  as  we  know,  decides  the  priority  of  inventions  in  Amer- 
ica. An  action  on  the  ground  of  this  omission  has  lately  been 
brought  against  Mr.  Bell,  in  the  Supreme  Court  of  the  Amer- 
ican Patent  Office,  to  set  aside  the  patent  granted  to  him.  If 
Mr.  Gray  did  not  appeal  before,  it  was  because  he  was  then 
wholly  occupied  with  experiments  on  the  system  of  harmonic 
telephone,  applied  to  telegraphic  communication,  and  he  had 
no  time  to  attend  to  the  matter. 

However  this  may  be,  Mr.  Bell  did  not  begin  to  give  serious 
attention  to  the  speaking  telephone  until  he  had  obtained  his 
patent,  and  his  efforts  were  soon  crowned  with  success :  a  few 
months  later  he  exhibited  his  speaking  telephone  at  Philadel- 
phia, which  has  from  that  time  attracted  so  much  public  atten- 
tion, and  which,  when  perfected  in  a  practical  point  of  view, 
reached  Europe  in  the  autumn  of  1877  under  the  form  we 
know. 

To  complete  this  summary  account  of  the  telephone,  we 
ought  to  say  that  since  its  success  a  good  many  claims  of  pri- 
ority have  arisen,  as  if  by  enchantment.  Mr.  John  Camack, 
of  English  origin,  has  among  others  claimed  the  invention  of 
the  telephone,  not  merely  relying  on  the  description  he  gave  of 
the  instrument  in  1865,  but  on  the  drawings  he  executed;  he 
even  adds,  that  if  he  had  not  lacked  means  for  its  construction, 
this  would  have  been  the  date  of  the  discovery  of  the  tele- 
phone. A  similar  pretension  has  been  put  forward  by  Mr. 
Dolbear,  a  fellow-cotfntryman  of  Mr.  Bell,  of  whose  claim  we 
shall  speak  presently. 

Signor  Manzetti,  of  Aosta,  says  the  same  thing,  asserting 
that  his  telephonic  invention  was  described  in  several  newspa- 
pers of  1865,  among  others  in  Le  Petit  Journal,  of  Paris,  on 
the  22d  November,  1865  ;  H  Diritto  at  Rome,  16th  July,  1865 ; 
UEcho  d'  Italia,  New  York,  9th  August,  1865  ;  I? Italia,  Flor- 
ence, 10th  August,  1865;  La  Comuna  d"1  Italia,  Genoa,  1st 
December,  1865;  La  Verita,  Novara,  4th  January,  1866;  H 


18  THE    TELEPHONE. 

Commercio,  Genoa,  6th  January,  1866.  It  is  true  that  no  de- 
scription of  the  system  was  given,  and  that  the  journals  in 
question  only  asserted  that  experiments  had  been  made,  which 
proved  that  the  practical  solution  of  the  problem  of  transmit- 
ting speech  by  electricity  became  possible  by  this  system.  At 
any  rate,  M.  Charles  Bourseul  must  still  have  the  credit  of  the 
priority  of  the  idea,  and,  in  our  opinion,  all  claims  made  after 
the  fact  only  merit  slight  consideration. 

Before  considering  Bell's  telephone,  and  the  different  modi- 
fications which  have  been  applied  to  it,  it  seems  worth  while,  in 
order  to  make  the  reader  perfectly  familiar  with  these  kinds 
of  instruments,  to  study  the  electro-musical  telephones  which 
preceded  it,  and  especially  that  of  M.  Reiss,  which  was  made 
in  1860,  and  became  the  starting-point  of  all  the  others.  We 
shall  find  that  these  instruments  have  very  important  appli- 
cations, and  that  telegraphy  will  probably  be  one  day  much 
advanced  by  their  use. 

MUSICAL  TELEPHONES. 

Telephone  of  M.  Reiss. — This  telephone  is,  as  far  as  the  re- 
production of  sound  is  concerned,  based  upon  Mr.  Page's  dis- 
coveries in  1837,  and,  as  regards  electric  transmission,  it  is 
based  on  the  vibrating  membrane  of  which  Mr.  L.  Scott  made 
use  in  his  phonautograph,  in  1855.  This  instrument  is  com- 
posed, like  telegraphic  systems,  of  two  distinct  parts,  a  sender 
and  a  receiver,  as  represented  in  Fig.  1.  • 

The  sender  was  virtually  composed  of  a  sounding-box,  K, 
having  on  its  upper  surface  a  large  circular  opening,  across 
which  a  membrane  was  stretched,  and  in  its  centre  there  was 
fitted  a  thin  disk  of  platinum,  o,  above  which  a  metallic  point, 
c,  was  fixed,  and  this,  together  with  the  disk,  constituted  the 
contact-breaker.  On  one  face  of  the  sounding-box  K  there 
was  a  sort  of  speaking-tube,  for  the  purpose  of  collecting  the 
sound,  and  directing  it  to  the  interior  of  the  box,  in  order  that 


M.  REISS  S    TELEPHONE. 


10 


it  might  then  react  upon  the  membrane.  Part  of  the  box  K 
is  broken  away  in  the  plate,  in  order  that  the  different  parts  of 
which  it  is  made  may  be  seen. 


Fiu.  1. 


The  rods  a,  c,  which  support  the  platinum  point  b,  are  in 
metallic  contact  with  a  Morse  key,  t,  placed  on  the  side  of  the 
box  K,  and  with  an  electro-magnet,  A,  which  belongs  to  a  tele- 
graphic system,  intended  to  exchange  the  signals  required 
to  start  the  action  of  the  two  instruments  at  their  respective 
stations. 

The  receiver  consists  of  a  sounding -box,  B,  on  which  rest 
two  supports,  d,  d,  bearing  an  iron  rod  of  the  thickness  of  a 
knitting-needle.  An  induction  coil  of  insulated  wire,  g,  is 
wound  round  this  rod,  and  the  whole  is  enclosed  by  the  lid  D, 
which  concentrates  the  sound  already  increased  by  the  sound- 


20  THE    TELEPHONE. 

ing-box:  for  this  purpose  the  box  is  provided  with  two  open- 
ings below  the  coil. 

The  circuit  is  completed  through  the  primary  of  this  coil 
by  the  two  terminals  3  and  4,  and  a  Morse  key,  t,  is  placed  at 
the  side  of  box  B,  in  order  to  exchange  signals. 

In  order  to  work  this  system,  the  speaking  instrument 
should  be  placed  before  the  opening  T,  and  this  instrument 
may  be  a  flute,  a  violin,  or  even  the  human  voice.  The  vibra- 
tions of  air  occasioned  by  these  instruments  cause  the  tele- 
phonic membrane  to  vibrate  in  unison,  and  the  latter,  rapidly 
moving  the  platinum  disk  o  to  and  from  the  point  5,  causes  a 
series  of  breaks  in  the  current,  which  are  repeated  in  the  iron 
wire  d  d,  and  transformed  into  metallic  vibrations,  of  which 
the  number  is  equal  to  that  of  the  sounds  successively  pro- 
duced. 

According  to  this  mode  of  action,  the  possibility  of  trans- 
mitting sounds  with  their  relative  value  becomes  intelligible ; 
but  it  is  equally  clear  .that  sounds  thus  transmitted  will  not 
have  the  timbre  of  those  which  produce  them,  since  the  tim- 
bre is  independent  of  the  number  of  vibrations,  and  it  must 
be  added  that  the  sounds  produced  by  M.  Reiss's  instrument 
were  as  shrill  as  those  of  a  child's  penny  trumpet,  and  by  no 
means  attractive.  The  problem  of  transmitting  musical  sounds 
by  electricity  was,  however,  really  solved,  and  it  can  be  said- 
with  truth  that  an  air  or  a  melody  could  be  heard  at  any  given 
distance. 

The  invention  of  this  telephone  dates,  as  we  have  seen,  from 
1860,  and  Professor  Heisler  speaks  of  it  in  his  treatise  of  tech- 
nical physics,  published  at  Vienna  in  1866;  he  even  asserts, 
in  the  article  which  he  devotes  to  the  subject,  that  although 
the  instrument  was  still  in  its  infancy,  it  was  capable  of  trans- 
mitting vocal  melodies,  and  not  merely  musical  sounds.  The 
system  was  afterward  perfected  by  M.  Vander  Weyde,  who, 
after  reading  the  account  published  by  M.  Heisler,  sought  to 


21 

make  the  box  of  the  sender  more  sonorous,  and  to  strenothen 
the  sounds  produced  by  the  receiver.  He  writes  as  follows  in 
the  American  Scientific  Journal : 

"In  1868  I  caused  two  telephones  to  be  made,  similar  to 
those  I  have  described,  and  I  exhibited  them  at  a  meeting  of 
the  Polytechnic  Club  of  the  American  Institute.  The  trans- 
mitted sounds  were  produced  at  the  farthest  extremity  of  the 
Cooper  Institute,  quite  outside  the  hall  in  which  the  audience 
sat :  the  receiver  was  placed  on  a  table  in  the  hall  itself.  The 
vocal  airs  were  faithfully  reproduced,  but  the  sound  was  rather 
weak  and  nasal.  I  then  tried  to  improve  the  instrument,  and 
I  first  obtained  stronger  vibrations  in  the  box  K  by  causing 
reverberation  from  the  sides  of  the  box,  by  means  of  hollow 
partitions.  I  next  intensified  the  sounds  produced  by  the  re- 
ceiver, by  introducing  several  iron  wires  into  the  coil  instead 
of  one.  These  improvements  were  submitted  to  the  meeting 
of  the  American  Association  for  the  Advancement  of  Science, 
which  was  held  in  1869,  and  it  was  considered  that  the  inven- 
tion contained  the  germ  of  a  new  method  of  telegraphic  trans- 
mission which  might  lead  to  important  results."  This  opinion 
was  soon  afterward  justified  by  the  discoveries  of  Bell  and 
Elisha  Gray. 

Messrs.  Cecil  and  Leonard  Wratfs  Telephone. — This  system, 
represented  in  Figs.  2  and  3,  is  simply  an  improvement  on  that 
of  M.  Reiss,  with  the  object  of  intensifying  the  effects  pro- 
duced. The  sender  is  provided  with  two  membranes  instead 
of  one,  and  its  receiver,  instead  of  being  formed  of  a  single 
iron  wire  covered  with  a  magnetizing  coil,  is  composed  of  two 
distinct  coils,  H,  H'  (Fig.  2),  placed  in  the  same  straight  line, 
and  within  which  are  two  iron  rods.  These  rods  are  fastened 
by  one  of  their  ends  to  two  copper  disks,  A,  B ;  these  disks 
are  maintained  in  a  fixed  position  by  screws,  I,  I',  and  the  two 
other  extremities  of  the  rods,  between  the  coils,  are  opposite 
each  other,  not  touching,  but  divided  by  a  very  small  interval. 


22  THE   TELEPHONE. 

The  instrument  is  set  upon  a  sounding-box,  in  which  there  is 
a  hole,  T,  in  the  space  corresponding  to  the  interval  between 
the  coils :  these  coils  communicate  with  four  terminals,  which 


FIG.  2. 

are  connected  with  the  electric  current  in  such  a  way  that  the 
adjacent  poles  of  the  two  rods  are  of  opposite  polarity,  thus 
forming  a  single  magnet,  divided  in  the  centre.  It  seems  that 
by  this  arrangement  the  sound  produced  becomes  much  more 
distinct. 

The  form  of  the  sender,  also,  is  somewhat  different  from  the 
one  we  have  previously  described :  the  upper  part,  instead  of 
being  horizontal,  is  rather  inclined,  as  it  appears  in  Fig.  3 ;  and 
the  opening  E,  through  which  the  sound  has  to  communicate 
with  the  vibrating  membrane,  occupies  a  great  part  of  the  up- 
per surface  of  the  box,  which  consequently  appears  to  be  some- 
what oblique.  The  second  membrane,  G,  which  is  of  caout- 
chouc, forms  a  sort  of  partition  which  divides  the  box  in  two, 
starting  from  the  upper  end  of  the  opening:  the  inventor 
states  that  this  will  protect  the  outer  membrane,  D,  from  the 
breath  and  other  injurious  effects,  while  increasing  the  force 
of  the  vibrations  produced  on  the  first  membrane,  as  in  a  drum. 
The  contact-breaker  itself  also  differs  from  the  one  in  M.  Reiss's 
instrument.  The  platinum  disk  b  is  only  placed  in  circuit  by 
means  of  two  slender  wires  of  platinum  or  steel,  which  are  im- 
mersed in  two  small  cups,  filled  with  mercury,  and  connected 


ELECTRIC    HARMONICA. 


23 


with  the  circuit.     In  this  way  the  movements  of  the  mem- 
brane D  are  free,  and  its  vibration  is  rendered  more  easy. 

The  circuit  is  also  broken  by  a  little  platinum  point  resting 
on  a  lever  with  a  spring-joint,  K  H,  which  is  above  the  disk : 
one  end  of  the  lever,  which  is  fixed  below  a  kind  of  Morse  key, 
M  I,  makes  it  possible  to  close  the  circuit  with  the  hand,  so  as 
to  give  the  signal  for  setting  the  apparatus  to  work. 


Fio.  3. 

Electric  Harmonica. — Long  before  M.  Reiss's  invention,  and 
consequently  still  longer  before  that  of  Mr.  Elisha  Gray,  I  men- 
tioned a  sort  of  electric  harmonica,  and  described  it  as  follows 
in  the  first  edition  of  my  "Expose  des  applications  de  1'Elec- 
tricite,"  published  in  1853  : 

"  The  power  possessed  by  electricity  to  set  metallic  plates  in 
motion  and  cause  their  vibration  has  been  used  for  the  pro- 
duction of  distinct  sounds,  which  can  be  combined  and  harmo- 
nized ;  but  in  addition  to  this  purely  physical  application,  elec- 
tro-magnetism has  come  to  the  aid  of  certain  instruments,  such 


24  THE    TELEPHONE. 

as  pianos,  organs,  etc.,  rendering  them  capable  of  being  played 
at  a  distance.  So  that  this  extraordinary  force  may  be  turned 
to  account  in  arts  which  are  apparently  the  least  susceptible 
of  any  application  of  electricity. 

"We  have  already  spoken  of  M.  de  la  Rive's  contact-break- 
er. It  is,  as  we  know,  an  iron  disk,  ired  to  a  steel  spring, 
and  maintained  in  a  fixed  position  opposite  to  an  electro-magnet 
by  another  spring  in  connection  with  one  branch  ^  of  the  cur- 
rent. As  the  other  branch,  after  passing  into  the  wire  of  the 
electro-magnet,  terminates  in  the  iron  disk  itself,  the  electro- 
magnet is  only  active  at  the  moment  when  the  disk  touches 
the  terminal  spring ;  at  the  moment  of  leaving  it,  the  magnet- 
ism ceases,  and  the  iron  disk  returns  to  its  normal  position, 
and  then  leaves  it  again.  In  this  way  a  vibration  is  produced, 
rapid  in  proportion  to  the  small  size  of  the  vibrating  disk,  and 
to  the  greatness  of  the  force  produced  by  the  approach  of  the 
disk  to  the  electro-magnet. 

"In  order  to  increase  the  acuteness  of  the  sounds,  one  or 
other  of  these  expedients  must  be  employed.  The  simplest 
way  is  to  use  a  screw  which  can  be  tightened  or  relaxed  at 
pleasure,  and  which  in  this  manner  removes  the  vibrating  disk 
to  a  greater  or  less  distance  from  the  electro-magnet.  This  is 
the  case  in  M.  Froment's  instrument,  and  by  this  means  he  has 
obtained  sounds  of  extraordinary  acuteness,  although  not  un- 
pleasant to  the  ear. 

"  M.  Frornent  has  not  applied  the  apparatus  to  a  musical  in- 
strument, but  it  is  evident  that  it  would  be  easy  to  do  so ;  it 
would  only  be  necessary  to  make  the  notes  of  a  key-board  act 
on  metallic  levers,  of  a  length  corresponding  to  the  position  re- 
quired by  the  disk  for  the  vibration  of  different  tones.  These 
different  levers,  resting  on  the  disk,  would  act  as  a  point  of 
contact,  but  the  point  would  vary  in  position,  according  to  the 
touch. 

"If  the  current  were  constant,  such  an  instrument  would 


ELECTRIC    HARMONICA.  25 

certainly  have  many  advantages  over  the  pipe  instruments 
which  are  in  use,  since  the  vibration  might  be  prolonged  at 
will  in  the  case  of  each  note,  and  the  sounds  would  be  softer; 
unfortunately  the  irregular  action  of  the  battery  makes  it  diffi- 
cult in  practice.  These  kinds  of  instruments  are  therefore 
only  used  as  a  means  ofc$3gulating  by  ear  the  force  of  the  bat- 
tery— a  much  more  convenient  regulator  than  the  rheometers, 
since  it  is  possible  to  estimate  by  them  the  variations  of  the 
battery  during  an  experiment  without  any  distraction  of  the 
mind." 

In  1856,  M.  Petrina,  of  Prague,  invented  an  analogous  ar- 
rangement, to  which  he  gave  the  name  of  electric  harmonica, 
although,  strictly  speaking,  he  had  not  thought  of  it  as  a  mu- 
sical instrument.  This  is  what  I  have  said  on  the  subject  in 
vol.  iv.  of  the  second  edition  of  my  "  Expose  des  applications 
de  PElectricite,"  published  in  1859  : 

"  The  principle  of  this  instrument  is  similar  to  that  of  Neef 's 
rheotome,  in  which  the  hammer  is  replaced  by  slender  rods, 
whose  vibrations  produce  a  sound.  Four  of  these  rods  are 
placed  side  by  side,  and  when  moved  by  keys,  and  arrested  by 
levers,  produce  combined  sounds  of  which  the  origin  may  be 
easily  shown." 

It  is  true  that  nothing  is  said  in  this  passage  of  the  capabil- 
ity possessed  by  these  instruments  of  being  played  at  a  dis- 
tance ;  but  this  idea  was  quite  legitimate,  and  German  periodi- 
cals assert  that  it  was  accomplished  by  M.  Petrina  even, before 
1856.  It  was  the  result  of  what  I  said  at  the  outset:  "that 
electro-magnetism  may  come  to  the  aid  of  certain  instruments, 
such  as  pianos,  organs,  etc.,  in  order  to  enable  them  to  be  played 
at  a  distance"  and  I  also  pointed  out  the  expedients  employed 
for  the  purpose,  and  even  for  setting  them  at  work,  under  the 
influence  of  a  small  musical-box.  I  did  not,  however,  ascribe 
importance  to  the  matter,  and  it  is  only  by  way  of  historical 
illustration  that  I  speak  of  these  systems. 

2 


26  THE    TELEPHONE. 

Telephone  by  Mr.  JElisha  Gray,  of  Chicago. — This  system, 
invented  in  1874,  is  in  reality  only  an  instrument  of  the  nat- 
ure of  those  which  preceded  it,  but  with  important  modifica- 
tions, which  made  it  possible  to  apply  it  usefully  to  telegraphy. 
In  an  early  model  he  made  use  of  an  induction  coil,  with  two 
helices,  one  over  the  other:  the  contact-breaker,  which  was 
vibrating,  was  multiple,  and  so  arranged  as  to  produce  vibra- 
tions numerous  enough  to  emit  sounds.  These  sounds  may, 
as  we  have  seen,  be  modified  by  this  arrangement,  according 
to  the  mode  in  which  the  instrument  is  adjusted,  and  if  there 
are  a  certain  number  of  such  contact-breakers  side  by  side, 
with  vibrating  disks  so  ordered  as  to  produce  the  different 
notes  of  the  scale  on  several  octaves,  it  becomes  possible,  by  a 
combination  of  certain  notes,  to  execute  on  this  new  kind  of 
instrument  a  piece  of  music  such  as  may  be  produced  by  a 
harmonium,  an  accordion,  or  any  other  instrument  with  blow- 
ers. The  contact-breakers  are  set  in  motion  by  means  of  the 
primary  current  of  the  induction  coil,  as  it  circulates  through 
one  or  other  of  the  electro-magnets  of  these  contact-breakers, 
actuated  by  the  lowering  of  the  notes  of  a  key-board  connect- 
ed with  them,  and  the  secondary  currents  which  arise  in  the 
coil,  in  consequence  of  the  interruptions  in  the  primary  cur- 
rents, transmit  the  corresponding  vibrations  to  a  remote  re- 
ceiver. There  is  an  analogy  between  this  instrument  and  the 
telephones  of  which  we  have  already  spoken  by  Reiss  and 
Wray,.but  the  effect  is  increased  by  Mr.  Gray's  modifications. 

We  represent  in  Fig.  4  the  arrangement  of  the  first  system. 
The  vibrators  are  A  and  A',  the  key-board  M  and  M',  the  in- 
duction coil  B,  and  the  receiver  C.  This  receiver  consists,  as 
we  see,  of  a  simple  electro -magnet,  N  N':  above  its  poles 
there  is  a  metal  cylindrical  case,  C,  of  which  the  bottom  is 
made  of  iron,  to  serve  as  an  armature.  This  box,  like  a  violin, 
is  pierced  with  two  holes  in  the  form  S,  to  serve  as  a  sounding- 
board  ;  and  Mr.  Elisha  Gray  has  ascertained  that  the.molecu- 


GKAY'S  TELEPHONE.  27 

lar  motion  which  takes  place  in  the  magnetic  core  and  its 
armature,  under  the  influence  of  alternate  magnetization  and 
demagnetization,  sufficed  to  produce  vibrations  corresponding 
to  the  velocity  of  these  alternations,  and  to  emit  sounds  which 
became  audible  when  they  were  magnified  by  the  sounding- 
board. 


FIG.  4. 


It  is  quite  intelligible  that  the  effect  obtained  in  this  system 
might  be  reproduced,  if,  instead  of  contact-breakers  or  electric 
rheotomes,  mechanical  contact-breakers  were  used  at  the  send- 
ing-station,  so  arranged  as  to  furnish  the  requisite  number  of 
breaks  in  the  current  which  communicates  the  vibrations  of 
the  different  notes  of  the  scale.  In  this  way  also  it  would  be 
possible  to  dispense  with  the  induction  coil,  by  causing  the 
current  which  has  been  broken  by  the  mechanical  contact- 
breaker  to  react  upon  the  receiver.  Mr.  Elisha  Gray  has,  more- 
over, made  a  different  arrangement  of  this  telephonic  system, 


28  THE    TELEPHONE. 

which  he  has  applied  to  telegraphy  for  simultaneous  electric 
transmissions,  of  which  we  shall  speak  presently. 

If  we  may  believe  Mr.  Elisha  Gray,  the  vibrations  transmit- 
ted by  the  secondary  currents  would  be  capable,  by  the  inter- 
vention of  the  human  body,  of  causing  the  sounds  to  be  re- 
produced at  a  distance  by  conducting  disks,  which  vibrate 
readily,  and  are  placed  on  a  sounding-box.  In  this  way  musi- 
cal sounds  may  be  evoked  from  copper  cylinders  placed  upon 
a  table,  from  a  metallic  disk  fastened  to  a  kind  of  violin,  from 
a  membrane  stretched  on  a  drum,  or  from  any  other  resonant 
substance,  by  touching  any  of  these  objects  with  one  hand, 
while  holding  the  end  of  the  line  with  the  other.  These 
sounds,  of  which  the  quality  must  vary  with  the  substance 
touched,  would  reproduce  the  transmitted  note  with  the  pre- 
cise number  of  vibrations  which  belong  to  it.1 

Mr.  Varletfs  Telephone. — This  is,  strictly  speaking,  merely 
a  musical  telephone  of  the  same  kind  as  that  of  Mr.  Gray,  but 
the  arrangement  of  the  receiver  is  original  and  interesting. 
This  part  of  the  instrument  essentially  consists  of  a  drum  of 
large  size  (three  or  four  feet  in  diameter),  within  which  is  a 
condenser  formed  of  four  sheets  of  tin-foil,  divided  by  sheets 
of  some  insulating  material,  and  with  a  surface  of  about  half 

1  Mr.  Gray,  in  an  article  inserted  in  the  Telegrapher  of  October  Yth,  1876, 
enters  into  full  details  of  this  mode  of  transmitting  sounds  by  the  tissues 
of  the  human  body,  and  he  gives  the  following  as  the  conditions  in  which 
it  must  be  placed  to  obtain  a  favorable  result : 

1.  The  electricity  must  be  of  a  high  tension,  in  order  to  have  an  effect 
perceptible  to  the  ear. 

2.  The  substance  employed  to  touch  the  metallic  plate  must  be  soft, 
flexible,  and  a  good  conductor,  up  to  the  point  of  contact :  it  must  then 
interpose  a  slight  resistance,  neither  too  great  nor  too  small. 

3.  The  disk  and  the  hand,  or  any  other  tissue,  must  not  only  be  in  con- 
tact, but  the  contact  must  result  from  rubbing  or  gliding  over  the  surface. 

4.  The  parts  in  contact  must  be  dry,  so  as  to  maintain  the  required  de- 
gree of  resistance. 


VAULEY'S  TELEPHONE.  29 

the  size  of  the  drum.  The  plates  of  the  condenser  are  placed 
parallel  to  the  membranes  of  the  drum,  and  very  little  removed 
from  its  surface. 

If  an  electric  charge  is  communicated  to  one  of  the  series  of 
conducting  plates  of  the  condenser,  those  which  correspond  to 
it  are  attracted,  and  if  they  were  movable  they  might  commu- 
nicate to  the  intervening  strata  of  air  a  movement  which,  on 
reaching  the  membranes  of  the  drum,  might,  by  a  series  of 
charges  in  rapid  succession,  cause  the  membranes  to  vibrate, 
and  thus  produce  sounds :  these  sounds  would  correspond  to 
the  number  of  charges  and  discharges  which  had  occurred. 
Since  these  charges  and  discharges  are  determined  by  the  con- 
tact of  the  two  plates  of  the  condenser,  at  the  extremities  of 
the  secondary  circuit  of  an  induction  coil,  of  which  the  primary 
circuit  has  been  duly  broken,  it  becomes  evident  that,  in  order 
to  cause  the  drum  to  emit  any  given  sound,  it  will  be  enough 
to  produce  the  number  of  vibrations  in  the  contact-breaker  of 
the  induction  coil  which  are  required  for  this  sound. 

The  means  employed  by  Mr.  Yarley  to  produce  these  inter- 
ruptions are  the  same  which  are  in  use  in  several  electrical  in- 
struments, and  especially  in  chronographs — an  electro-magnetic 
tuning-fork,  regulated  so  as  to  emit  the  sound  required.  This 
tuning-fork  may,  by  acting  as  contact-breaker,  react  on  the  pri- 
mary current  of  the  induction  coil ;  if  the  number  of  the  tun- 
ing-forks equals  that  of  the  musical  notes  which  are  to  be  trans- 
mitted, and  if  the  electro-magnets  which  set  them  in  motion 
are  connected  with  the  key-board  of  a  piano,  it  would  be  possi- 
ble to  transmit  a  melody  to  a  distance  by  this  system,  as  well 
as  by  that  of  Mr.  Elisha  Gray. 

The  peculiarity  of  this  system  consists  in  the  reproduction 
of  sounds  by  the  action  of  a  condenser ;  and  we  shall  presently 
see  that  this  idea,  adopted  by  Messrs.  Pollard  and  Gamier,  led 
to  interesting  results. 

Singing  Condenser  of  MM.  Pollard  and  Gamier. — This  in- 


30  THE   TELEPHONE. 

strument,  which  astonishes  all  who  hear  it,  attracted  public  at- 
tention in  London  some  time  ago.  It  is  difficult  to  say  why 
its  fame  was  not  greater,  since  much  attention  has  been  be- 
stowed on  less  curious  instruments.  It  is  a  fact  that  we  have 
been  able,  thanks  to  MM.  Pollard  and  Gamier,  to  hear  songs 
issue  from  a  sort  of  copybook,  so  as  to  become  audible  through- 
out the  room.  The  songs  thus  reproduced  are  certainly  not 
always  perfectly  true ;  yet  when  the  person  who  sings  into  the 
sender  is  a  musician,  and  understands  how  to  make  use  of  it, 
the  condenser  in  question  will  emit  sounds  somewhat  resem- 
bling those  of  the  violoncello  or  the  hautbois. 

The  singing  instrument  consists  of  a  condenser,  K,  formed 
of  thirty  sheets  of  paper,  laid  one  over  the  other,  from  nine  to 
thirteen  centimetres  in  thickness :  between  these,  twenty-eight 
sheets  of  tin-foil,  from  six  to  twelve  centimetres  thick,  are  in- 
tercalated, so  joined  as  to  form  the  two  plates  of  the  condenser. 
For  this  purpose  the  pair  sheets  are  joined  together  at  one  end 
of  the  copybook,  and  the  odd  sheets  at  the  other  end.  This 
system  is  fastened  to  a  stiff  carton,  after  taking  care  to  bind  it 
with  a  strip  of  paper,  and  the  sheets  of  tin-foil  are  joined  to 
the  two  ends  of  the  condenser  by  two  copper  rims,  D,  D,  which 
are  provided  with  terminals  for  the  circuit  wire,  and  in  this 
way  the  singing  instrument  is  constructed.  A  somewhat  heavy 
weight,  placed  upon  the  condenser  to  compress  the  sheets,  does 
not  in  any  way  prevent  it  from  working ;  and  this  vitiates  the 
theory  first  put  forward  to  explain  its  effects,  that  the  sheets 
were  moved  by  attraction. 

The  sending  instrument  consists  of  a  sort  of  telephone  with- 
out a  handle,  E,  of  which  the  vibrating  disk  is  formed  of  a  very 
thin  plate  of  tin.  A  cylindrical  piece  of  carbon,  C,  is  fastened 
to  its  centre,  and  is  supported  by  another  cylinder  of  the  same 
material,  H.  This  rests  on  a  transverse  piece  of  wood,  A  B, 
jointed  on  the  side  A,  on  the  edge  opposite  to  the  box,  by 
means  of  a  regulating  screw,  V.  An  arched  spring,  R  (the  end 


SINGIXG    CONDENSER. 


31 


of  a  watch-spring),  placed  across  this  piece  of  wood  gives  it  a 
certain  elasticity  beneath  the  pressure,  and  this  elasticity  is  nec- 
essary in  order  that  the  instrument  may  act  properly,  and  it 
thus  becomes  a  sort  of  microphone  with  a  diaphragm. 


FIG.  5. 

The  tin  plate  is  put  into  communication  with  one  pole  of  a 
battery,  P,  of  six  Leclanche  cells,  and  the  lower  carbon  cylinder, 
H,  corresponds  to  the  primary  helix  of  an  induction  coil,  M, 
previously  connected  with  the  second  pole  of  the  battery.  Fi- 
nally, the  two  extremities  of  the  secondary  helix  of  the  coil,  a 
and  6,  are  in  immediate  connection  with  the  two  plates,  D,  D', 
of  the  condenser. 


32  THE    TELEPHONE. 

This  secondary  helix  should  consist  of  twenty  strands  of  wire 
No.  32,  covered  with  silk,  and  the  primary  helix  is  made  of  five 
strands  of  wire  No.  16.  The  length  of  the  coil  should  not  ex- 
ceed seven  centimetres,  and  the  diameter  of  the  core  of  fine 
iron  wire  ought  to  be  about  one  centimetre. 

In  order  to  produce  song  on  the  condenser,  the  sender  must 
be  so  regulated  that  the  two  carbons  C  and  H  do  not  touch 
each  other  in  their  normal  condition,  but  they  should  be  so 
close  that  in  singing  the  vibrations  of  the  disk  L  L  may  effect 
the  needful  contacts.  The  adjustment  can  be  easily  made  by 
the  touch,  and  by  uttering  the  same  note  until  it  is  repeated 
by  the  condenser.  If  three  notes,  given  in  succession,  are 
faithfully  reproduced,  the  instrument  may  be  assumed  to  be 
properly  regulated,  and,  in  order  to  make  it  work,  it  is  enough 
to  apply  the  mouth  to  the  mouth-piece  as  it  is  applied  to  a 
reed  pipe. 

In  order  to  obtain  a  satisfactory  result,  the  disk  of  the  instru- 
ment must  be  heard  to  vibrate,  as  in  a  flute  a  Toignon.  Instead 
of  carbons,  contacts  of  platinum  may  be  used;  but  when  ar- 
ranged as  we  have  described,  the  instrument  may  be  employed 
for  several  purposes,  as  we  shall  see  presently.  This  instrument 
is  made  by  MM.  Chardin  and  Prayer.  M.  Janssens  has  made 
the  system  more  portable  by  fastening  the  sender,  represented 
in  Fig.  5,  to  a  handle  in  which  the  induction  coil  is  placed :  the 
instrument  then  resembles  an  ordinary  telephone,  and  the  vibra- 
tion of  the  diaphragm  is  made  more  easy  by  piercing  two  holes 
in  it.  On  the  side  of  the  sending-box,  above  and  below  the 
diaphragm,  there  are  binding  screws  in  connection  with  the  end 
of  the  handle,  since  the  instrument  may  be  used  as  an  ordinary 
telephonic  sender,  and  even  as  a  telephonic  receiver. 

SPEAKING  TELEPHONES. 

We  have  seen  that  the  telephones  just  described  can  only 
transmit  musical  sounds,  since  they  can  merely  repeat  simple 


STRING   TELEPHONES.  33 

vibrations,  in  greater  or  less  number,  it  is  true,  but  not  in  si- 
multaneous combinations  like  those  which  reproduce  articulate 
sounds.  Up  to  the  time  of  Mr.  Bell's  invention,  the  transmis- 
sion of  speech  could  only  take  place  with  the  aid  of  acoustic 
tubes,  or  of  the  string  telephones  of  which  we  have  spoken. 
Although  these  instruments  have  no  connection  with  the  ob- 
ject of  our  study  in  this  work,  we  have  thought  it  necessary  to 
say  a  few  words  about  them,  since  they  may  sometimes  be 
combined  with  electric  telephones,  and  also  represent  the  first 
stage  of  the  invention. 

String  Telephones. — These  instruments,  which  have  flooded 
the  cities  of  Europe  for  several  years,  since  the  date  of  the  in- 
vention was  1867,  are  interesting  in  themselves,  and  we  are  sur- 
prised that  they  have  not  hitherto  taken  a  place  in  the  collec- 
tions of  physical  science.  They  are  made  of  two  metal  or 
card-board  tubes,  in  the  form  of  a  cylindrical  cone :  one  end  is 
closed  by  a  tightly  stretched  membrane  of  parchment,  in  the 
centre  of  which  the  cord  or  string  intended  to  connect  the  two 
cylinders  is  fastened  by  a  knot.  When  two  such  tubes  are 
connected  in  this  way,  and  the  cord  is  tightly  stretched,  as  in 
Fig.  6,  it  is  only  necessary  to  apply  one  tube  to  the  ear,  while 
another  speaks  into  the  opening  of  the  other  tube :  the  words 
spoken  by  the  latter  are  instantly  transmitted,  and  it  is  even 
possible  to  converse  in  quite  an  undertone.  Under  these  con- 
ditions the  vibrations  of  the  membrane  affected  by  the  voice 
are  mechanically  transmitted  to  the  other  membrane  by  the 
string,  which,  as  Robert  Hooke  declared  in  1667,  is  a  better 
transmitter  of  sound  than  the  air.  In  this  way  it  is  possible 
to  communicate  at  a  distance  of  170  yards,  and  the  size  and 
nature  of  the  cord  have  some  influence.  The  sellers  of  these 
instruments  say  that  the  best  results  are  obtained  from  silken 
cords,  and  the  worst  from  those  made  of  hemp.  Cords  of 
plaited  cotton  are  usually  employed  for  the  sake  of  cheapness. 

In  some  patterns  the  tubes  are  so  arranged  as  to  present,  be- 

o* 


34 


THE    TELEPHONE. 


tween  the  membrane  and  the  mouth,  a  diaphragm  pierced  with 
a  hole,  and  the  instrument  somewhat  resembles  a  bell  with  its 
base  bored  and  closed  again  a  little  above  the  parchment  mem- 
brane; but  I  have  not  observed  that  this  pattern  is  decidedly 
superior  to  the  others. 


FIG.  6. 


It  has  also  been  asserted  that  horn-shaped  tubes  of  nickel 
silver  are  to  be  preferred,  of  which  I  am  equally  doubtful.  At 
any  rate,  these  instruments  have  produced  unexpected  results ; 
and  although  their  practical  use  is  very  limited,  they  are  inter- 
esting from  a  scientific  point  of  view,  and  are  instructive  toys 
for  children. 

Mr.  Millar,  of  Glasgow,  declares  that  the  effect  produced  by 
these  telephones  depends  very  much  on  the  nature  of  the 
string,  the  way  in  which  it  is  attached,  and  the  way  in  which 
the  membrane  is  fastened  to  the  mouth-piece. 

Improvements  made  in  the  String  Telephone. — The  amazing 
effects  of  the  Bell  telephones  have  lately  brought  the  string 
telephones,  which  were  only  regarded  as  children's  toys,  again 


IMPROVEMENTS.  35 

into  fashion.  Since  they  have  made  it  possible  to  transmit  to 
several  persons  the  words  reproduced  by  an  electric  telephone, 
means  have  been  sought  for  combining  them  usefully  with  the 
latter,  and  the  best  mode  of  making  them  speak  on  a  string 
presenting  several  angles  has  been  sought  for:  it  has  been 
shown  that,  under  the  usual  conditions,  these  instruments  only 
speak  distinctly  when  the  string  is  stretched  in  a  right  line. 
To  solve  this  problem,  it  occurred  to  M.  A.  Breguet  to  make 
use  of  a  sort  of  tambourine  for  the  supports,  with  the  string 
passed  through  their  centre ;  the  sound  conveyed  by  that  part 
of  the  string  which  is  in  connection  with  the  speaking-horn 
causes  the  membrane  of  the  tambourine  to  vibrate,  which  again 
communicates  the  vibration  to  the  next  portion  of  string.  In 
this  way  the  angles  may  be  multiplied  at  will,  and  the  string 
may  be  supported  throughout  the  length  compatible  with  this 
kind  of  telephone,  which  does  not  exceed  112  yards. 

M.  A.  Breguet  has  also  invented  a  system  of  relays  to  ac- 
complish the  same  object.  He  makes  the  strings  terminate  in 
two  membranes  which  close  the  two  openings  of  a  brass  cylin- 
der. The  sounds  reproduced  on  one  of  these  membranes  react 
upon  the  other,  which  vibrates  under  its  influence,  as  if  it  were 
affected  by  the  voice.  The  cylinder  then  acts  as  an  ordinary 
acoustic  tube,  and  its  form  may  be  varied  at  pleasure. 

M.  A.  Badet,  on  February  1st,  1878,  succeeded  in  making 
string  telephones  in  an  analogous  way,  and  he  used  parchment 
stretched  upon  frames  which  acted  as  resonant  boards.  The 
string  was  fixed  in  the  centre  of  the  membrane,  and  made  with 
it  the  angle  desired. 

Several  scientific  men,  among  others  Messrs.  Wheatstone, 
Cornu,  and  Mercadier,  have  long  been  occupied  about  these 
ways  of  transmission  by  wire,  and  Messrs.  Millar,  Heaviside, 
and  Nixon  have  lately  made  some  interesting  experiments,  on 
which  we  must  say  a  few  words.  Mr.  Millar  ascertained  that 
by  means  of  a  telegraphic  wire,  stretched  and  connected  by 


36  THE    TELEPHONE. 

two  copper  wires  with  two  vibrating  disks,  musical  sounds 
might  be  conveyed  to  a  distance  exceeding  160  yards,  and  that 
by  stretching  these  wires  through  a  house,  and  connecting 
them  with  mouth  and  ear  holes  in  different  rooms,  communica- 
tion between  them  became  perfectly  easy. 

For  the  vibrating  disks  he  employed  wood,  metal,  or  gutta- 
percha,  in  the  form  of  a  drum,  with  wires  fixed  in  the  centre. 
The  sound  seems  to  become  more  intense  in  proportion  to  the 
thickness  of  the  wire. 

Messrs.  Heaviside  and  Nixon,  in  their  experiments  at  New- 
castle-on-Tyne,  have  ascertained  that  the  most  effective  wire 
was  No.  4  of  the  English  gauge.  They  employed  wooden 
disks  an  eighth  of  an  inch  in  thickness,  and  these  may  be 
placed  in  any  part  of  the  length  of  the  wire.  When  the  wire 
was  well  stretched  and  motionless,  it  was  possible  to  hear  what 
was  said  at  a  distance  of  230  yards,  and  it  seems  that  Mr. 
Huntley,  by  using  very  thin  iron  diaphragms,  and  by  insula- 
ting the  line  wire  on  glass  supports,  was  able  to  transmit  speech 
for  2450  feet,  in  spite  of  the  zigzags  made  by  the  line  on  its 
supports. 

Mr.  Graham  BelVs  Electric  Telephone. — Telephonic  instru- 
ments were  at  this  stage  when  Bell's  telephone  was  shown  at 
the  Philadelphia  Exhibition  of  1876.  Sir  William  Thompson 
did  not  hesitate  to  call  it  "  the  wonder  of  wonders,"  and  it  in- 
stantly attracted  universal  attention,  although  there  was  at  first 
much  incredulity  as  to  its  genuineness.  This  telephone,  in 
fact,  reproduced  articulate  words,  a  result  which  surpassed  all 
the  conceptions  of  physicists.  In  this  case  it  was  no  longer  a 
conception,  to  be  treated  as  visionary  until  there  was  proof  to 
the  contrary :  the  instrument  spoke,  and  even  spoke  so  loud- 
ly that  it  was  not  necessary  to  apply  the  ear.  Sir  William 
Thompson  spoke  to  this  effect,  on  the  subject  at  the  meeting 
of  the  British  Association  at  Glasgow  in  September,  1876 : 

"  In  the  department  of  telegraphs  in  the  United  States  I  saw 


BELL'S  TELEPHONE.  37 

and  heard  Mr.  Elisha  Gray's  electric  telephone,  of  wonderful 
construction,  which  can  repeat  four  despatches  at  the  same 
time  in  the  Morse  code,  and,  with  some  improvements  in  detail, 
this  instrument  is  evidently  capable  of  a  fourfold  delivery.  In 
the  Canadian  department  I  heard  *  To  be  or  not  to  be  ?  There's 
the  rub,'  uttered  through  a  telegraphic  wire,  and  its  pronuncia- 
tion by  electricity  only  made  the  rallying  tone  of  the  mono- 
syllables more  emphatic.  The  wire  also  repeated  some  extracts 
from  New  York  papers.  With  my  own  ears  I  heard  all  this, 
distinctly  articulated  through  the  slender  circular  disk  formed 
by  the  armature  of  an  electro-magnet.  It  was  my  fellow-jury- 
man, Professor  Watson,  who,  at  the  other  extremity  of  the 
line,  uttered  these  words  in  a  loud  and  distinct  voice,  while  ap- 
plying his  mouth  to  a  tightly  stretched  membrane  provided 
with  a  small  piece  of  soft  iron,  which  executed  movements  cor- 
responding to  the  sound  vibrations  of  the  air  close  to  an  elec- 
tro-magnet introduced  into  the  circuit.  This  discovery,  the 
wonder  of  wonders  in  electric  telegraphy,  is  due  to  a  young 
fellow-countryman  of  our  own,  Mr.  Graham  Bell,  a  native  of 
Edinburgh,  and  now  naturalized  in  New  York. 

"It  is  impossible  not  to  admire  the  daring  invention  by 
which  we  have  been  able  to  realize  with  these  simple  expedi- 
ents the  complex  problem  of  reproducing  by  electricity  the 
tones  and  delicate  articulations  of  voice  and  speech;  and  it 
was  necessary,  in  order  to  obtain  this  result,  to  find  out  the 
means  of  varying  the  intensity  of  the  current  in  the  same  pro- 
portion as  the  inflections  of  the  sound  emitted  by  the  voice." 

If  we  are  to  believe  Mr.  Graham  Bell,  the  invention  of  the 
telephone  was  not  due  to  a  spontaneous  and  fortunate  concep- 
tion :  it  was  the  result  of  his  long  and  patient  studies  in  acous- 
tic science,  and  of  the  labors  of  the  physicists  who  preceded 
him.1  His  father,  Mr.  Alexander  Melville  Bell,  of  Edinburgh, 

1  He  cites  the  following  names  in  his  account  of  electric  telephony : 


38  THE   TELEPHONE. 

had  studied  this  science  deeply,  and  had  even  succeeded  in 
representing  with  great  ingenuity  the  adaptation  of  the  vocal 
organs  for  the  emission  of  sound.  It  was  natural  that  he 
should  instil  a  taste  for  his  favorite  studies  into  his  son's  mind, 
and  they  made  together  numerous  researches  in  order  to  dis- 
cover the  relations  which  exist  between  the  different  elements 
of  speech  in  different  languages,  and  the  musical  relations  of 
vowels.  It  is  true  that  several  of  these  researches  had  been 
made  by  M.  Helmholtz,  and  under  more  favorable  conditions ; 
but  these  studies  were  of  great  use  to  Mr.  Bell  when  he  was 
afterward  occupied  with  the  telephone,  and  Helmholtz's  exper- 
iments, which  he  repeated  with  one  of  his  friends,  Mr.  Hellis, 
of  London,  concerning  the  artificial  reproduction  of  vowels  by 
means  of  electric  tuning-forks,  launched  him  into  the  study  of 
the  application  of  electricity  to  acoustic  instruments.  He  first 
invented  a  system  of  an  electric  harmonica  with  a  key-board, 
in  which  the  different  sounds  of  the  scale  were  reproduced 
by  electric  diapasons  of  different  forms,  adapted  to  different 
notes,  and  which,  when  set  in  motion  by  the  successive  lower- 
ing of  the  keys,  could  reproduce  sounds  corresponding  to  the 
notes  touched,  just  as  in  an  ordinary  piano. 

He  next,  as  he  tells  us,  turned  his  attention  to  telegraphy, 
and  thought  of  making  the  Morse  telegraphs  audible  by  causing 
the  electro-magnetic  organ  to  react  on  sounding  contacts.  It 
is  true  that  this  result  had  already  been  obtained  in  the  sound- 
ers used  in  telegraphy,  but  he  thought  that  by  applying  this 
system  to  his  electric  harmonica,  and  by  employing  such  an 
intensifying  instrument  as  Helmholtz's  resonator  at  the  receiv- 
ing-station, it  would  be  possible  to  obtain  through  a  single 
wire  simultaneous  transmissions  which  should  be  due  to  the 

Page,  Marrian,  Beatson,  Gassiot,  De  la  Rive,  Matteucci,  Guillemin,  Wert- 
heim,  Wartmann,  Janniar,  Joule,  Laborde,  Legat,  Reiss,  Poggendorf,  Du 
Moncel,  Delezenne,  Gore,  etc.  Vide  Mr.  Bell's  paper,  in  the  Journal  of  the 
Society  of  Telegraphic  Engineers  in  London,  vol.  vi.  p.  390,  391. 


ELECTRIC   CURRENTS. 


39 


action  of  the  voice.  We  shall  see  presently  that  this  idea  was 
realized  almost  at  the  same  time  by  several  inventors,  among 
others  by  M.  Paul  Lacour,  of  Copenhagen,  Mr.  Elisha  Gray,  of 
Chicago,  and  Messrs.  Edison  and  Varley. 

Mr.  Bell's  study  of  electric  telephones  really  dates  from  this 
time,  and  he  passed  from  complex  to  simple  instruments,  mak- 
ing a  careful  study  of  the  different  modes  of  vibration  which 
arise  from  different  modes  of  electric  action.  The  following  is 
an  abstract,  with  the  omission  of  more  technical  details,  of  the 
paper  read  by  Mr.  Bell  to  the  Society  of  Telegraphic  Engineers, 
London,  October  31st,  1877: 

If  the  intensity  of  an  electric  current  is  represented  by  the 
ordinatcs  of  a  curve,  and  the  duration  of  breaks  in  the  current 
by  the  abscissa,  the  given  curve  may  represent  the  waves  of 
the  positive  or  negative  current  respectively,  above  and  below 
the  line  of  X,  and  these  waves  will  be  more  or  less  accentuated, 
just  as  the  transmitted  currents  are  more  or  less  instantaneous. 

If  the  currents  which  are  interrupted  to  produce  a  sound 
are  quite  instantaneous  in  their  manifestation,  the  curve  repre- 
sents a  series  of  isolated  indentations,  as  we  see  in  Fig.  7 ; 


•fr 


-4'M'I 


Fis  T. 


40 


THE    TELEPHONE. 


a. 

0|0|             /    N 

[ 

rJol              v!/ 

r       a. 

B 

ilililil 

R 

/.«• 


FIG.  8. 


and  if  the  interruptions  are  so  made  as  only  to  produce  dif- 
ferences of  intensity,  the  curve  is  presented  under  the  form 
of  Fig.  8.  Finally,  if  the  emissions  of  current  are  so  ordered 
that  their  intensity  alternately  increases  and  diminishes,  the 


e'\ 

l\ 

f 

o 

0 

B 

ilili 

•  I  . 

FIG.  9. 


ANALYSIS    OF    CURRENTS. 


41 


curve  takes  the  form  represented  in  Fig.  9.  In  the  first  case, 
the  currents  are  intermittent;  in  the  second,  pulsatory;  in  the 
third  case,  they  are  undulatory. 

These  currents  are  necessarily  positive  or  negative,  accord- 
ing to  their  position  above  or  below  the  line  a?,  and  if  they  are 
alternately  reversed,  the  curves  present  the  form  given  in  Fig. 
10,  curves  which  essentially  differ  from  the  first,  not  merely 
in  the  different  form  of  the  indentations,  but  especially  in  the 
suppression  of  the  extra  current,  which  is  always  found  in  the 
pulsatory  and  undulatory  currents. 


FIG.  10. 

The  two  former  systems  of  currents  have  long  been  in  use 
for  the  electric  transmission  of  musical  sounds,  of  which  we 
have  an  interesting  example  in  Reiss's  telephone,  already  de- 
scribed. But  Mr.  Bell  claims  to  have  been  the  first  to  employ 
the  undulatory  currents,  which  made  it  possible  to  solve  the 
problem  of  transmitting  speech.1  In  order  to  estimate  the  im- 

1  This  statement  is  disputed  by  Mr.  Elisha  Gray,  owing,  as  we  shall  see, 
to  a  misunderstanding  as  to  the  word  undulatory  current. 


42  iHE    TELEPHONE. 

portance  of  this  discovery,  it  will  be  enough  to  analyze  the  ef- 
fects produced  with  these  different  systems  of  currents  when 
several  notes  of  varying  pitch  are  to  be  combined. 

Fig.  7  shows  a  combination  in  which  the  styles  a,  a',  of  two 
sending  instruments  cause  the  interruption  of  the  current  from 
the  same  battery  B,  so  that  the  given  vibrations  should  be  be- 
tween them  in  the  relation  of  a  tierce  major,  that  is,  in  the  re- 
lation of  four  to  five.  Under  such  conditions  the  currents  are 
intermittent,  and  four  contacts  of  a  are  produced  in  the  same 
space  of  time  as  the  five  contacts  of  a',  and  the  corresponding- 
electric  intensities  will  be  represented  by  the  indentations  we 
see  in  A2  and  in  Ba :  the  combination  of  these  intensities,  A2-f 
B2,  will  produce  the  indentations  at  unequal  intervals  which  may 
be  observed  on  the  third  line.  It  is  evident  that  although  the 
current  maintains  a  uniform  intensity,  there  is  less  time  for 
the  breaks  when  the  interrupting  styles  act  together  than  when 
they  act  separately,  so  that  when  there  are  a  number  of  con- 
tacts effected  simultaneously  by  styles  working  at  different  de- 
grees of  velocity,  the  effects  produced  will  have  the  effect  of  a 
continuous  current.  The  maximum  number  of  distinct  effects 
which  can  be  produced  in  this  way  will,  however,  greatly  de- 
pend on  the  relation  which  exists  between  the  durations  of  the 
make  and  break  of  the  current.  The  shorter  the  contacts  are, 
and  the  longer  the  breaks,  the  more  numerous  will  be  the  ef- 
fects transmitted  without  confusion,  and  vice  versa. 

By  the  aid  of  pulsatory  currents  the  transmission  of  musical 
sounds  is  effected  in  the  way  indicated  in  Fig.  8,  and  it  is  seen 
that  when  they  are -produced  simultaneously,  the  result  A2-f-B7 
is  analogous  to  that  which  would  be  produced  by  a  continuous 
current  of  minimum  intensity. 

In  the  case  of  undulatory  currents  the  result  is  different,  but 
in  order  to  produce  them  it  is  necessary  to  have  recourse  to  in- 
ductive effects,  and  Fig.  9  indicates"  the  manner  in  which  the 
experiment  should  be  made.  In  this  case,  "  the  current  from 


PHOXAUTOGRAPH.  43 

the  battery  B  is  thrown  into  waves  by  the  inductive  action  of 
iron  or  steel  reeds,  M,  M,  vibrated  in  front  of  electro-magnets, 
e,  0,  placed  in  circuit  with  the  battery :  Aa  and  Ba  represent 
the  undulations  caused  in  the  current  by  the  vibration  of  the 
magnetized  bodies,  and  it  will  be  seen  that  there  are  four  undu- 
lations of  Ba  in  the  same  time  as  five  undulations  of  Aa.  The 
resultant  effect  upon  the  main  line  is  expressed  by  the  curve 
Aa  +  Ba,  which  is  the  algebraical  sum  of  the  sinusoidal  curves 
Aa  and  B3.  A  similar  effect  is  produced  when  reversed  undu- 
latory  currents  are  employed,  as  in  Fig.  10,  where  the  current 
is  produced  by  the  vibration  of  permanent  magnets  united  upon 
a  circuit,  without  a  voltaic  battery. 

"It  will  be  understood  from  Figs.  9  and  10  that  the  effect 
of  transmitting  musical  signals  of  different  pitches  simultane- 
ously along  a  single  wire  is  not  to  obliterate  the  vibratory 
character  of  the  current,  as  in  the  case  of  intermittent  and  pul- 
satory currents,  but  to  change  the  shapes  of  the  electrical  undu- 
lations. In  fact,  the  effect  produced  upon  the  current  is  pre- 
cisely analogous  to  the  effect  produced  in  the  air  by  the  vibra- 
tion of  the  inducing  bodies  M,  M'.  Hence  it  should  be  possi- 
ble to  transmit  as  many  musical  tones  simultaneously  through 
a  telegraph  wire  as  through  the  air." 

After  applying  these  principles  to  the  construction  of  a  tele- 
graphic system  for  multiple  transmissions,  Mr.  Bell  lost  no  time 
in  making  use  of  his  researches  to  improve  the  vocal  training 
of  deaf-mutes.  "  It  is  well  known,"  he  said,  "  that  deaf-mutes 
are  dumb  merely  because  they  are  deaf,  and  that  there  is  no 
defect  in  their  vocal  organs  to  incapacitate  them  from  utter- 
ance. Hence  it  was  thought  that  my  father's  system  of  picto-* 
rial  symbols,  popularly  known  as  visible  speech,  might  prove  a 
means  whereby  we  could  teach  the  deaf  and  dumb  to  use  their 
vocal  organs  and  to  speak.  The  great  success  of  these  experi- 
ments urged  upon  me  the  advisability  of  devising  methods  of 
exhibiting  the  vibrations  of  sound  optically,  for  use  in  teaching 


44  THE    TELEPHONE. 

the  deaf  and  dumb.  For  some  time  I  carried  on  experiments 
with  the  manometric  capsule  of  Koenig,  and  with  the  phonau- 
tograph  of  Leon  Scott.  The  scientific  apparatus  in  the  Insti- 
tute of  Technology  in  Boston  was  freely  placed  at  my  disposal 
for  these  experiments,  and  it  happened  that  at  that  time  a  stu- 
dent of  the  Institute  of  Technology,  Mr.  Maurey,  had  invented 
an  improvement  upon  the  phonautograph.  He  had  succeeded 
in  vibrating  by  the  voice  a  stylus  of  wood  about  a  foot  in  length 
which  was  attached  to  the  membrane  of  the  phonautograph, 


^/Wvwvvv^^/wVA/WWy^^ 


f 


VVAA/Va/vVVOAA/V/VlA/YWWVta^  I 


I1 


FIG.  11. 


and  in  this  way  he  had  been  enabled  to  obtain  enlarged  trac- 
ings upon  a  plane  surface  of  smoked  glass.  With  this  appara- 
tus I  succeeded  in  producing  very  beautiful  tracings  of  the  vi- 
brations of  the  air  for  vowel  sounds.  Some  of  these  tracings 
are  shown  in  Fig.  11.  I  was  much  struck  with  this  improved 
form  of  apparatus,  and  it  occurred  to  me  that  there  was  a  re- 
markable likeness  between  the  manner  in  which  this  piece  of 
wood  was  vibrated  by  the  membrane  of  the  phonautograph 


PH  ON AUTOGRAPH. 


45 


and  the  manner  in  which  the  ossiculce  of  the  human  ear  were 
moved  by  the  tympanic  membrane.  I  determined,  therefore,  to 
construct  a  phonautograph  modelled  still  more  closely  upon  the 
mechanism  of  the  human  ear,  and  for  this  purpose  I  sought  the 
assistance  of  a  distinguished  aurist  in  Boston,  Dr.  Clarence  J. 
Blake.  He  suggested  the  use  of  the  human  ear  itself  as  a 
phonautograph,  instead  of  making  an  artificial  imitation  of  it. 
The  idea  was  novel,  and  struck  me  accordingly,  and  I  requested 
my  friend  to  prepare  a  specimen  for  me,  which  he  did.  The 
apparatus,  as  finally  constructed,  is  shown  in  Fig.  12.  The 


Fio.  12. 


46 


THE    TELEPHONE. 


stapes  was  removed,  and  a  stylus  of  hay  about  an  inch  in  length 
was  attached  to  the  end  of  the  incus.  Upon  moistening  the 
membrana  tympani  and  the  ossiculce  with  a  mixture  of  glyce- 
rine and  water,  the  necessary  mobility  of  the  parts  was  obtained  ; 
and  upon  singing  into  the  external  artificial  ear  the  stylus  of 
hay  was  thrown  into  vibration,  and  tracings  were  obtained  upon 
a  plane  surface  of  smoked  glass  passed  rapidly  underneath. 
While  engaged  in  these  experiments  I  was  struck  with  the  re- 
markable disproportion  in  weight  between  the  membrane  and 
the  bones  that  were  vibrated  by  it.  It  occurred  to  me  that  if 
a  membrane  as  thin  as  tissue-paper  could  control  the  vibration 
of  bones  that  were,  compared  to  it,  of  immense  size  and  weight, 
why  should  not  a  larger  and  thicker  membrane  be  able  to  vi- 
brate a  piece  of  iron  in  front  of  an  electro-magnet,  in  which 
case  the  complication  of  steel  rods  shown  in  my  first  form  of 
telephone  could  be  done  away  with,  and  a  simple  piece  of  iron 
attached  to  a  membrane  be  placed  at  either  end  of  the  tele- 
graphic circuit  ? 


FIG.  13. 

"For  this  purpose  I  attached  the  reed  A  (Fig.  13)  loosely 
by  one  extremity  to  the  uncovered  pole,  h,  of  the  magnet,  and 
fastened  the  other  extremity  to  the  centre  of  a  stretched  mem- 
brane of  gold-beater's-skin,  n.  I  presumed  that,  upon  speaking 
in  the  neighborhood  of  the  membrane  n,  it  would  be  thrown 
into  vibration,  and  cause  the  steel  reed  A  to  move  in  a  similar 
manner,  occasioning  undulations  in  the  electrical  current  that 
would  correspond  to  the  changes  in  the  density  of  the  air  dur- 


BELL   TELEPHONE.  47 

ing  the  production  of  the  sound ;  and  I  further  thought  that 
the  change  of  the  intensity  of  the  current  at  the  receiving  end 
would  cause  the  magnet  there  to  attract  the  reed  A'  in  such  a 
manner  that  it  should  copy  the  motion  of  the  reed  A,  in  which 
case  its  movements  would  occasion  a  sound  from  the  membrane 
nf  similar  in  timbre  to  that  which  had  occasioned  the  original 
vibration. 

"  The  results,  however,  were  unsatisfactory  and  discouraging. 
My  friend  Mr.  Thomas  A.  Watson,  who  assisted  me  in  this  first 
experiment,  declared  that  he  heard  a  faint  sound  proceed  from 
the  telephone  at  his  end  of  the  circuit,  but  I  was  unable  to 
verify  his  assertion.  After  many  experiments  attended  by  the 
same  only  partially  successful  results,  I  determined  to  reduce 
the  size  and  weight  of  the  spring  as  much  as  possible.  For 
this  purpose  I  fastened  a  piece  of  clock  spring,  about  the  size 
and  shape  of  my  thumb-nail,  firmly  to  the  centre  of  the  dia- 
phragm, and  had  a  similar  instrument  at  the  other  end  (Fig. 
14) ;  we  were  then  enabled  to  obtain  distinctly  audible  effects. 


FIG.  14. 


I  remember  an  experiment  made  with  this  telephone,  which  at 
the  time  gave  me  great  satisfaction  and  delight.  One  of  the 
telephones  was  placed  in  my  lecture-room  in  the  Boston  Uni- 


48  THE    TELEPHONE. 

versity,  and  the  other  in  the  basement  of  the  adjoining  build- 
ing. One  of  my  students  repaired  to  the  distant  telephone  to 
observe  the  effects  of  articulate  speech,  while  I  uttered  the 
sentence,  *  Do  you  understand  what  I  say  ?'  into  the  telephone 
placed  in  the  lecture-hall.  To  my  delight  an  answer  was  re- 
turned through  the  instrument  itself,  articulate  sounds  pro- 
ceeded from  the  steel  spring  attached  to  the  membrane,  and  I 
heard  the  sentence,  '  Yes,  I  understand  you  perfectly.'  It  is  a 
mistake,  however,  to  suppose  that  the  articulation  was  by  any 
means  perfect,  and  expectancy  no  doubt  had  a  great  deal  to  do 
with  my  recognition  of  the  sentence  ;  still,  the  articulation  was 


FIG.  15. 

there,  and  I  recognized  the  fact  that  the  indistinctness  was  en- 
tirely due  to  the  imperfection  of  the  instrument.  I  will  not 
trouble  you  by  detailing  the  various  stages  through  which  the 
apparatus  passed,  but  shall  merely  say  that  after  a  time  I  pro- 
duced the  form  of  instrument  shown  in  Fig.  15,  which  served 
very  well  as  a  receiving  telephone.  In  this  condition  my  inven- 
tion was  exhibited  at  the  Centennial  Exhibition  in  Philadelphia. 
The  telephone  shown  in  Fig.  14  was  used  as  a  transmitting 
instrument,  and  that  in  Fig.  15  as  a  receiver,  so  that  vocal  com- 
munication was  only  established  in  one  direction. 

"  The  articulation  produced  from  the  instrument  shown  in 
Fig.  15  was  remarkably  distinct,  but  its  great  defect  consisted 


BELL  TELEPHONE. 


49 


in  the  fact  that  it  could  not  be  used  as  a  transmitting  instru- 
ment, and  thus  two  telephones  were  required  at  each  station, 
one  for  transmitting  and  one  for  receiving  spoken  messages. 

"  It  was  determined  to  vary  the  construction  of  the  tele- 
phone, and  I  sought,  by  changing  the  size  and  tension  of  the 
membrane,  the  diameter  and  thickness  of  the  steel  spring,  the 
size  and  power  of  the  magnet,  and  the  coils  of  insulated  wire 
around  their  poles,  to  discover  empirically  the  exact  effect  of 
each  element  of  the  combination,  and  thus  to  deduce  a  more 
perfect  form  of  apparatus.  It  was  found  that  a  marked  in- 
crease in  the  loudness  of  the  sounds  resulted  from  shortening 
the  length  of  the  coils  of  wire,  and  by  enlarging  the  iron  dia- 
phragm which  was  glued  to  the  membrane.  In  the  latter  case, 
also,  the  distinctness  of  the  articulation  was  improved.  Final- 
ly, the  membrane  of  gold-beater's-skin  was  discarded  entirely, 
and  a  simple  iron  plate  was  used  instead,  and  at  once  intelligi- 
ble articulation  was  obtained.  The  new  form  of  instrument  is 
that  shown  in  Fig.  16,  and,  as  had  been  long  anticipated,  it 


FIG.  16. 

was  proved  that  the  only  use  of  the  battery  was  to  magnet- 
ize the  iron  core  of  the  magnet,  for  the  effects  were  equally 
audible  when  the  battery  was  omitted  and  a  rod  of  magnetized 
steel  substituted  for  the  iron  core  of  the  magnet. 

"  It  was  my  original  intention,  and  it  was  always  claimed  by 
me,  that  the  final  form  of  telephone  would  be  operated  by  per- 

3 


50  THE    TELEPHONE. 

manent  magnets  in  place  of  batteries,  and  numerous  experi- 
ments had  been  carried  on  by  Mr.  Watson  and  myself  privately 
for  the  purpose  of  producing  this  effect. 

"  At  the  time  the  instruments  were  first  exhibited  in  public 
the  results  obtained  with  permanent  magnets  were  not  nearly 
so  striking  as  when  a  voltaic  battery  was  employed,  where- 
fore we  thought  it  best  to  exhibit  only  the  latter  form  of  in- 
strument. 

"  The  interest  excited  by  the  first  published  accounts  of  the 
operation  of  the  telephone  led  many  persons  to  investigate  the 
subject,  and  I  doubt  not  that  numbers  of  experimenters  have 
independently  discovered  that  permanent  magnets  might  be 
employed  instead  of  voltaic  batteries.  Indeed  one  gentleman, 
Professor  Dolbear,  of  Tufts  College,  not  only  claims  to  have' 
discovered  the  magneto  -  electric  telephone,  but  I  understand 
charges  me  with  having  obtained  the  idea  from  him  through 
the  medium  of  a  mutual  friend. 

"A  still  more  powerful  form  of  apparatus  was  constructed 
by  using  a  powerful  compound  horseshoe  magnet  in  place  of 

the  straight  rod  which  had  been 
previously  used  (see  Fig.  17). 
Indeed  the  sounds  produced  by 
means  of  this  instrument  were 
of  sufficient  loudness  to  be 
faintly  audible  to  a  large  audi- 
ence, and  in  this  condition  the 
instrument  was  exhibited  in  the 
Essex  Institute,  in  Salem,  Mas- 
sachusetts, on  February  12th,  1877,  on  which  occasion  a  short 
speech  shouted  into  a  similar  telephone  in  Boston,  sixteen 
miles  away,  was  heard  by  the  audience  in  Salem.  The  tones 
of  the  speaker's  voice  were  distinctly  audible  to  an  audience  of 
600  people,  but  the  articulation  was  only  distinct  at  a  distance 
of  about  six  feet.  On  the  same  occasion,  also,  a  report  of  the 


BELL  TELEPHONE. 


51 


lecture  was  transmitted  by  word  of  mouth  from  Salem  to  Bos- 
ton, and  published  in  the  papers  the  next  morning. 

"From  the  form  of  telephone  shown  in  Fig.  16  to  the  pres- 
ent form  of  the  instrument  (Fig.  18)  is  but  a  step.  It  is,  in 
fact,  the  arrangement  of  Fig.  16  in  a  portable  form,  the  magnet 


FIG.  IS. 

N  S  being  placed  inside  the  handle,  and  a  more  convenient 
form  of  mouth-piece  provided. 

"And  here  I  wish  to  express  my  indebtedness  to  several  sci- 
entific friends  in  America  for  their  co-operation  and  assistance. 
I  would  specially  mention  Professor  Peirce  and  Professor 
Blake,  of  Brown  University,  Dr.  Channing,  Mr.  Clarke,  and  Mr. 
Jones.  It  was  always  my  belief  that  a  certain  ratio  would  be 
found  between  the  several  parts  of  a  telephone,  and  that  the 
size  of  the  instrument  was  immaterial ;  but  Professor  Peirce 
was  the  first  to  demonstrate  the  extreme  smallness  of  the 
magnets  which  might  be  employed.  The  convenient  form  of 
mouth-piece  shown  in  Fig.  17,  now  adopted  by  me,  was  invent- 
ed solely  by  my  friend  Professor  Peirce." 

Another  form  of  transmitting  telephone  exhibited  in  Phila- 
delphia, intended  for  use  with  the  receiving  telephone  (Fig.  15), 
is  represented  by  Fig.  19. 

A  platinum  wire  attached  to  a  stretched  membrane  com- 
pleted a  voltaic  circuit  by  dipping  into  water.  Upon  speaking 


52 


THE   TELEPHONE. 


to  the  membrane,  articulate  sounds  proceeded  from  the  tele- 
phone in  the  distant  room.  The  sounds  produced  by  the  tele- 
phone became  louder  when  dilute  sulphuric  acid,  or  a  saturated 


FIG.  19. 

solution  of  salt,  was  substituted  for  the  water.  Audible  effects 
were  also  produced  by  the  vibration  of  plumbago  in  mercury, 
in  a  solution  of  bichromate  of  potash,  in  salt  and  water,  in 
dilute  sulphuric  acid,  and  in  pure  water. 

Mr.  Bell  goes  on  to  say  : 

"  I  have  found,  also,  that  a  musical  tone  proceeds  from  a 
piece  of  plumbago  or  retort  carbon  when  an  intermittent  cur- 
rent of  electricity  is  passed  through  it,  and  I  have  observed  the 
most  curious  audible  effects  produced  by  the  passage  of  re- 
versed intermittent  currents  through  the  human  body.  A 
rheotome  was  placed  in  circuit  with  the  primary  wires  of  an 
induction  coil,  and  the  fine  wires  were  connected  with  two 
strips  of  brass.  One  of  these  strips  was  held  closely  against 


BELL'S  EXPERIMENTS.  53 

the  ear,  and  a  loud  sound  proceeded  from  it  whenever  the  oth- 
er slip  was  touched  with  the  other  hand.  The  strips  of  brass 
were  next  held  one  in  each  hand.  The  induced  currents  occa- 
sioned a  muscular  tremor  in  the  fingers.  Upon  placing  my 
forefinger  to  my  ear,  a  loud  crackling  noise  was  audible,  seem- 
ingly proceeding  from  the  finger  itself.  A  friend  who  was 
present  placed  my  finger  to  his  ear,  but  heard  nothing.  I  re- 
quested him  to  hold  the  strips  himself.  He  was  then  distinct- 
ly conscious  of  a  noise  (which  I  was  unable  to  perceive)  pro- 
ceeding from  his  finger.  In  this  case  a  portion  of  the  induced 
currents  passed  through  the  head  of  the  observer  when  he 
placed  his  ear  against  his  own  finger ;  and  it  is  possible  that 
the  sound  was  occasioned  by  a  vibration  of  the  surfaces  of  the 
ear  and  finger  in  contact. 

"When  two  persons  receive  a  shock  from  a  RuhmkorfFs 
coil  by  clasping  hands,  each  taking  hold  of  one  wire  of  the 
coil  with  the  free  hand,  a  sound  proceeds  from  the  clasped 
hands.  The  effect  is  not  produced  when  the  hands  are  moist. 
When  either  of  the  two  touches  the  body  of  the  other,  a  loud 
sound  comes  from  the  parts  in  contact.  When  the  arm  of  one 
is  placed  against  the  arm  of  the  other,  the  noise  produced  can 
be  heard  at  a  distance  of  several  feet.  In  all  these  cases  a 
slight  shock  is  experienced  so  long  as  the  contact  is  pre- 
served. The  introduction  of  a  piece  of  paper  between  the 
parts  in  contact  does  not  materially  interfere  with  the  pro- 
duction of  the  sounds,  but  the  unpleasant  effects  of  the  shock 
are  avoided. 

"When  an  intermittent  current  from  a  Ruhmkorff's  coil  is 
passed  through  the  arms,  a  musical  note  can  be  perceived  when 
the  ear  is  closely  applied  to  the  arm  of  the  person  experiment- 
ed upon.  The  sound  seems  to  proceed  from  the  muscles  of 
the  forearm  and  from  the  biceps  muscle.  Mr.  Elisha  Gray1 

1  Elisha  Gray.     Eng.  Pat,  Spec.  No.  2646,  Aug.  1874. 


54  THE   TELEPHONE. 

has  also  produced  audible  effects  by  the  passage  of  electricity 
through  the  human  body. 

"  An  extremely  loud  musical  note  is  occasioned  by  the  spark 
of  a  Ruhmkorff's  coil  when  the  primary  circuit  is  made  and 
broken  with  sufficient  rapidity ;  when  two  rheotomes  of  differ- 
ent pitch  are  caused  simultaneously  to  open  and  close  the 
primary  circuit,  a  double  tone  proceeds  from  the  spark. 

"A  curious  discovery,  which  may  be  of  interest  to  you,  has 
been  made  by  Professor  Blake.  He  constructed  a  telephone 
in  which  a  rod  of  soft  iron,  about  six  feet  in  length,  was  used 
instead  of  a  permanent  magnet.  A  friend  sang  a  continuous 
musical  tone  into  the  mouth -piece  of  a  telephone,  like  that 
shown  in  Fig.  17,  which  was  connected  with  -the  soft  iron  in- 
strument alluded  to  above.  It  was  found  that  the  loudness  of 
the  sound  produced  in  this  telephone  varied  with  the  direction 
in  which  the  iron  rod  was  held,  and  that  the  maximum  effect 
was  produced  when  the  rod  was  in  the  position  of  the  dipping- 
needle.  This  curious  discovery  of  Professor  Blake  has  been 
verified  by  myself. 

"When  a  telephone  is  placed  in  circuit  with  a  telegraph  line, 
the  telephone  is  found  seemingly  to  emit  sounds  on  its  own 
account.  The  most  extraordinary  noises  are  often  produced, 
the  causes  of  which  are  at  present  very  obscure.  One  class  of 
sounds  is  produced  by  the  inductive  influence  of  neighboring 
wires  and  by  leakage  from  them,  the  signals  of  the  Morse 
alphabet  passing  over  neighboring  wires  being  audible  in  the 
telephone,  and  another  class  can  be  traced  to  earth  currents 
upon  the  wire,  a  curious  modification  of  this  sound  revealing 
the  presence  of  defective  joints  in  the  wire. 

"  Professor  Blake  informs  me  that  he  has  been  able  to  use 
the  railroad  track  for  conversational  purposes  in  place  of  a  tel- 
egraph-wire, and  he  further  states  that  when  only  one  tele- 
phone was  connected  with  the  track  the  sounds  of  Morse  op- 
erating were  distinctly  audible  in  the  telephone,  although  the 


BELL'S  EXPERIMENTS.  55 

nearest  telegraph-wires  were  at  least  forty  feet  distant;  and 
Professor  Peirce  has  observed  the  most  curious  sounds  pro- 
duced from  a  telephone  in  connection  with  a  telegraph-wire 
during  the  aurora  borealis." 

Mr.  Bell  went  on  to  describe  instances  in  which  airs  sung  or 
played  upon  a  musical  instrument  are  transmitted  by  a  tele- 
phone, when  it  is  not  known  whence  they  come;  but  the 
strongest  proof  of  the  extraordinary  sensibility  of  this  instru- 
ment consists  in  its  becoming  possible  by  its  means  to  trans- 
mit speech  through  bodies  which  might  be  supposed  to  be 
non-conductors.  Thus  communication  with  the  earth  through 
the  human  body  can  be  made  in  spite  of  the  intervention  of 
shoes  and  stockings ;  and  it  may  even  be  effected  if,  instead 
of  standing  on  the  ground,  the  person  stands- on  a  brick  wall. 
Only  hewn  stone  and  wood  are  a  sufficient  hinderance  to  com- 
munication, and  if  the  foot  touches  the  adjoining  ground,  or 
even  a  blade  of  grass,  it  is  enough  to  produce  electric  mani- 
festations. 

Mr.  Bell  says  in  conclusion  : 

"  The  question  will  naturally  arise,  Through  what  length  of 
wire  can  the  telephone  be  used  ?  In  reply  to  this  I  may  say 
that  the  maximum  amount  of  resistance  through'  which  the  un- 
dulatory  current  will  pass,  and  yet  retain  sufficient  force  to  pro- 
duce an  audible  sound  at  the  distant  end,  has  yet  to  be  deter- 
mined ;  no  difficulty  has,  however,  been  experienced  in  labora- 
tory experiments  in  conversing  through  a  resistance  of  60,000 
ohms,  which  has  been  the  maximum  at  my  disposal.  On  one 
occasion,  not  having  a  rheostat  at  hand,  I  may  mention  having 
passed  the  current  through  the  bodies  of  sixteen  persons,  who 
stood  hand-in-hand.  The  longest  length  of  real  telegraph  line 
through  which  I  have  attempted  to  converse  has  been  about 
250  miles.  On  this  occasion  no  difficulty  was  experienced  so 
long  as  parallel  lines  were  not  in  operation.  Sunday  was  chosen 
as  the  day  on  which  it  was  probable  other  circuits  would  be  at 


56  THE    TELEPHONE. 

rest.  Conversation  was  carried  on  between  myself  in  New  York, 
and  Mr.  Thomas  A.  Watson  in  Boston,  until  the  opening  of 
business  upon  the  other  wires.  When  this  happened  the  vocal 
sounds  were  very  much  diminished,  but  still  audible.  It  seemed, 
indeed,  like  talking  through  a  storm.  Conversation,  though 
possible,  could  be  carried  on  with  difficulty,  owing  to  the  dis- 
tracting nature  of  the  interfering  currents. 

"  I  am  informed  by  my  friend  Mr.  Preece  that  conversation 
has  been  successfully  carried  on  through  a  submarine  cable,  six- 
ty miles  in  length,  extending  from  Dartmouth  to  the  Island  of 
Guernsey,  by  means  of  hand  telephones." 

Mr.  Elisha  Gray's  Share  in  the  Invention  of  the  Telephone. 
— We  have  seen  that  if  Mr.  Bell  was  the  first  to  construct  the 
speaking  telephone  in  a  practical  form,  Mr.  Gray  had  at  the 
same  time  conceived  the  idea  of  an  instrument  also  capable  of 
reproducing  speech,  and  the  description  given  of  it  in  his  ca- 
veat was  so  precise  that  if  it  had  been  made  from  his  design  it 
would  have  acted  perfectly.  This  was,  in  fact,  afterward  proved 
by  him.  In  order  that  our  readers  may  judge  from  their  own 
knowledge  of  the  share  which  should  be  ascribed  to  Mr.  Elisha 
Gray  in  the  invention  of  the  telephone,  we  reproduce  in  Fig.  20 
the  drawing  which  accompanied  the  caveat  in  question. 

The  sender,  as  we  see,  is  composed  of  a  sort  of  tube,  closed 
at,  its  lower  end  by  a  membrane  to  which  a  platinum  wire  is 
fixed  ;  this  wire  dips  into  a  liquid  of  moderate  conducting  pow- 
er, and  an  electrode  made  of  platinum,  in  communication  with 
a  battery,  is  fixed  at  the  bottom  of  the  vessel  containing  the 
liquid.  The  receiver  is  composed  of  an  electro  -  magnet,  of 
which  the  armature  is  fixed  to  the  centre  of  a  membrane, 
stretched  on  a  kind  of  resonator  or  ear-trumpet  which  is  held 
to  the  ear,  and  the  two  instruments  are  united  by  the  line  wire 
as  we  see  in  the  plate. 

Under  these  conditions,  the  undulatory  currents  necessary 
for  the  reproduction  of  speech  were  obtained  in  a  mode  analo- 


GKAY   TELEPHONE. 


gous  to  that  pointed  out  by  Mr.  Bell  in  his  specification,  that 
is,  by  the  variations  of  resistance  in  the  liquid  layer  interposed 


FIG.  20. 

between  the  platinum  wires  of  the  transmittei: ;  and  their  ac- 
tion, exerted  on  an  electro-magnet,  of  which  the  armature  was 
fixed  on  the  diaphragm  of  the  resonator,  was  produced  under 
more  favorable  conditions  than  in  Mr.  Bell's  specification  (see 
Fig.  13),  since  that  gentleman"  regards  this  arrangement  (repre^ 
sented  in  Fig.  14)  as  an  important  improvement  on  his  first 
conception. 

The  whole  importance  of  the  invention  rests  on  the  interven- 
tion of  undulatory  currents,  which,  as  we  have  seen,  are  indis- 
pensable for  the  reproduction  of  speech,  and  it  concerns  us  to 
know  whether  it  was  Mr.  Bell  or  Mr.  Gray  who  first  declared 
their  importance ;  for  in  both  the  specifications  deposited  on 
February  14th,  1876,  the  use  of  undulatory  currents  was  de- 
clared to  be  indispensable.  Mr.  Gray  asserts  that  he  had  rec- 
ognized their  importance  for  the  transmission  of  combined 
sounds  as  early  as  1874 ;  but  Mr.  Bell  believes  that  the  undula- 

3* 


58  THE    TELEPHONE. 

tory  currents  mentioned  by  Mr.  Gray  at  that  time  were  only 
currents  analogous  to  those  he  had  designated  under  the  name 
of  pulsatory  currents,  which  we  have  represented  in  Fig.  8.  We 
have  seen  that  since  these  currents  only  represent  the  abrupt 
elevations  and  depressions  of  intensity,  they  are  unfit  for  the 
reproduction  of  articulate  sounds,  which,  on  the  contrary,  de- 
mand that  the  variations  of  intensity  should  result  from  suc- 
cessive efforts,  in  exact  correspondence  with  all  the  inflections 
of  the  sonorous  vibrations  effected  by  the  voice.  Mr.  Bell's 
claim  to  priority  on  this  question  has  been  recognized  by  the 
American  Patent  Office,  since  he  has  been  placed  in  possession 
of  the  patent.  However  this  may  be,  Mr.  Gray's  telephonic 
system  was  complete,  and  we  see  in  it,  as  we  have  already  said, 
the  origin  of  the  battery  telephones,  which  have  recently  pro- 
duced such  important  results.  Let  us  now  consider  the  rela- 
tion which  this  system  bears  to  Mr.  Bell's. 

The  Bell  system,  as  we  have  seen,  although  making  use  of 
a  battery  in  the  first  instance,  only  obtained  the  diminution 
and  increase  of.  electric  force  necessary  for  the  articulation  of 
words  by  means  of  induction  currents  produced  by  the  move- 
ments of  an  armature  of  soft  iron — currents  of  which  the  in- 
tensity was  consequently  due  to  the  range  and  inflections  of 
these  movements.  The  battery  only  intervened  in  order  to 
communicate  magnetic  force  to  the  inducer.  This  use  of  in- 
duced currents  in  telephonic  transmissions  was  already  of  great 
importance,  since  various  experiments  subsequently  made  have 
proved  their  superiority  to  voltaic  currents  for  this  purpose. 
But  experience  soon  convinced  Mr.  Bell  that  a  powerful  in- 
ductive apparatus  worked  by  a  battery  was  not  only  unneces- 
sary for  the  action  of  this  apparatus,  but  that  a  permanent 
magnet,  very  small  and  weak,  would  provide  sufficient  currents. 
This  discovery,  in  which,  as  we  have  seen,  Mr,  Peirce  had  some 
share,  was  of  great  importance,  since  it  became  possible  to  re- 
duce the  size  of  the  instrument  considerably,  so  as  to  make  it 


MB.  OKAY'S  CLAIM  TO  THE  TELEPHONE.  59 

portable  and  adapted  for  sending  and  receiving;  and  it  was 
shown  that  the  telephone  was  the  most  sensitive  of  all  instru- 
ments in  revealing  the  action  of  currents.  If,  therefore,  Mr. 
Bell  was  not  the  first  to  employ  the  successful  mode  of  trans- 
mitting articulate  words,  it  must  be  said  that  he  sought,  like 
Mr.  Gray,  to  solve  the  problem  by  means  of  undulatory  cur- 
rents, and  that  he  obtained  these  currents  by  the  effect  of  in- 
duction, a  system  which,  as  soon  as  it  was  perfected,  led  to 
the  important  results  with  which  we  are  all  acquainted.  If  he 
had  only  given  to  the  astonished  world  an  instrument  capable 
of  reproducing  speech  telegraphically,  his  fame  would  be  great ; 
for  this  problem  had  hitherto  been  regarded  as  insoluble. 

Mr.  Gray's  claims  to  the  invention  of  the  telephone  are  given 
in  the  following  summary  from  a  very  interesting  work,  entitled 
"  Experimental  Researches  on  Electro-harmonic  Telegraphy  and 
Telephony :" 

"I.I  was  the  first  to  discover  the  means  of  transmitting 
compound  sounds  and  variable  inflections  through  a  closed 
circuit  by  means  of  two  or  more  electric  waves. 

"2.  I  assert  that  I" was  the  first  to  discover  and  utilize  the 
mode  of  reproducing  vibrations  by  the  use  of  a  magnet  re- 
ceiver constantly  supplied  with  electric  action. 

"  3.  I  also  assert  that  I  was  the  first  to  construct  an  instru- 
ment consisting  of  a  magnet  with  a  circular  diaphragm  of  mag- 
netic substance,  supported  by  its  edge  at  a  little  distance  from 
the  poles  of  a  magnet,  and  capable  of  being  applied  to  the 
transmission  and  reception  of  articulate  sounds." 

It  is  a  curious  fact,  worth  recording  here,  that  Mr.  Yates,  of 
Dublin,  in  1865,  when  trying  to  improve  Reiss's  telephone,  real- 
ized to  a  certain  extent  Mr.  Gray's  conception  of  the  liquid 
transmitter;  for  he  introduced  into  the  platinum  contacts  of 
Mr.  Reiss's  instrument  a  drop  of  water,  which  adapted  it  for 
the  reproduction  of  articulate  sounds.  However,  no  notice 
was  then  taken  of  this  result. 


60  THE    TELEPHONE. 


EXAMINATION  INTO  THE  FUNDAMENTAL  PRINCIPLES  ON 
WHICH  BELL'S  TELEPHONE  IS  BASED. 

Although  the  preceding  account  would  suffice  to  make  the 
principle  of  Bell's  telephone  intelligible  to  persons  acquainted 
with  electric  science,  this  would  not  be  the  case  with  the  ma- 
jority of  our  readers,  and  we  therefore  think  it  necessary  to 
enter  into  some  details  as  to  the  source  of  the  electric  currents 
which  are  employed  in  telephonic  transmissions.  These  details 
seem  to  us  the  more  necessary,  since  many  persons  still  believe 
that  Bell's  telephones  are  not  electric,  because  they  do  not  re- 
quire a  battery,  and  they  are  often  confounded  with  string 
telephones,  so  that  the  difference  of  price  between  Bell's  in- 
struments and  those  hawked  in  the  streets  seems  astonishing. 

Without  defining  what  is  meant  by  an  electric  current, 
which  would  be  too  elementary,  we  may  say  that  electric  cur- 
rents can  be  produced  by  different  causes,  and  that,  in  addi- 
tion to  those  which  are  due  to  batteries,  strong  currents  are 
also  produced  by  the  force  exerted  by  magnets  on  a  conduct- 
ing circuit  properly  arranged.  Such  currents  are  called  induc- 
tion currents,  and  are  used  in  Bell's  telephone.  In  order  to 
understand  how  they  are  developed  under  these  conditions,  it 
will  be  enough  to  examine  what  takes  place  when  the  pole  of 
a  magnet  is  brought  near  to,  and  withdrawn  from,  a  closed 
circuit.  To  do  this,  let  us  suppose  a  copper  wire  attached  to 
a  galvanometer  in  the  form  of  a  circle,  and  that  one  pole  of  a 
permanent  magnet  is  directed  toward  the  centre  of  the  circle. 
Now  observe  what  happens : 

1.  At  the  moment  when  the  magnet  approaches  an  electric 
current  arises,  causing  the  galvanometer  to  deviate  to  one  side. 
This  deviation  will  be  great  in  proportion  to  the  extent  of  the 
movement,  and  the  tension  of  the  current  will  be  great  in  pro- 
portion to  the  abruptness  of  the  movement.  The  current  will, 
however,  be  only  instantaneous. 


ELECTRIC   CURRENTS.  61 

2.  At  the  moment  when  the  magnet  is  withdrawn,  a  fresh 
current  of  the  same  nature  will  arise,  but  it  will  appear  in  an 
opposite  direction  from  the  former.     It  will  be  what  is  called 
a  direct  current,  because  it  is  in  the  same  direction  as  the  mag- 
netic current  of  the  magnet  which  produces  it,  while  the  other 
current  is  called  inverse. 

3.  If,  instead  of  advancing  or  withdrawing  the  magnet  by 
means  of  a  single  movement,  it  is  advanced  in  jerks,  a  succes- 
sion of  currents  in  the  same  direction  is  produced,  of  which 
the  existence  can  be  ascertained  by  the  galvanometer  when 
there  is  a  sufficient  interval  between  the  movements,  but  when 
the  intervals  are  very  slight  the  currents  are  interfused;  and 
since  inverse  effects  take  place  when  the  magnet  is  moved  in 
a  contrary  direction,  the  needle  of  the  galvanometer  follows 
the  movements  of  the  magnet,  and  to  a  certain  extent  stereo- 
types them. 

4.  If,  instead  of  reacting  o»  a  simple  closed  circuit,  the  mag- 
net exerts  its  force  on  a  considerable  number  of  circumvolu- 
tions of  this  circuit,  that  is,  on  a  bobbin  of  coiled  wire,  the  ef- 
fects will  be  considerably  increased,  and  they  will  be  still  greater 
if  there  be  a  magnetic  core  within  the  bobbin,  since  the  induc- 
ing action  will  then  be  more  effectually  exerted  throughout  the 
bobbin.     As  the  magnetic   core,  when  it  is  magnetized  and 
demagnetized  under  the  influence  of  its  approach  to  or  with- 
drawal from  the  inducing  magnet,  is  subject  to  the  reaction 
from  all  the  fluctuations  which  occur  in  the  movements  of  the 
magnet,  the  induced  currents  which  ensue  are  perfectly  defined. 

5.  If,  instead  of  a  movable  magnet,  we  suppose  it  to  be  fixed 
in  the  centre  of  the  coil,  the  induced  currents  of  which  we  have 
spoken  may  then  be  determined  by  modifying  its  force.     In 
order  to  do  so,  it  is  enough  that  an  iron  armature  should  react 
upon  its  poles.    When  this  armature  is  brought  close  to  one  of 
the  poles,  or  to  both  at  once,  it  acquires  force,  and  produces -an 
inverse  current,  that  is,  a  current  in  the  direction  which  would 


62  THE    TELEPHONE. 

have  corresponded  to  an  approach  of  the  magnet  to  the  closed 
circuit.  On  its  withdrawal  the  inverse  effect  is  produced ;  but 
in  both  cases  the  induced  currents  correspond  with  the  extent 
and  direction  of  the  movements  accomplished  by  the  armature, 
and  consequently  they  may  reproduce  its  movements  by  their 
effects.  If  this  armature  is  an  iron  plate,  which  vibrates  under 
the  influence  of  any  sound  in  this  disposition  of  the  electro- 
magnetic system,  the  alternate  movements  of  the  plate  will  be 
transformed  into  the  induced  currents,  and  these  will  be  strong- 
er or  weaker,  more  or  less  definite,  according  to  the  range  and 
complexity  of  the  vibrations :  they  will,  however,  be  undulato- 
ry,  since  they  will  always  result  from  successive  and  continuous 
movements,  and  will  consequently  be  in  the  conditions  which, 
as  we  have  seen,  are  required  for  the  transmission  of  speech. 

As  for  the  action  produced  upon  the  receiver — that  is,  on  the 
instrument  for  reproducing  speech — it  is  somewhat  complex, 
and  we  shall  have  occasion  to  speak  of  it  presently ;  but  we 
can  get  a  general  impression  of  it,  if  we  consider  that  the  ef- 
fects produced  by  the  induced  currents  of  variable  intensity, 
which  traverse  the  coil  of  the  electro -magnetic  system,  must 
determine,  by  the  magnetizations  and  demagnetizations  which 
ensue,  the  vibrations  of  the  armature  disk ;  these  vibrations, 
more  or  less  amplified  and  defined,  exactly  represent  those  of 
the  disk  before  which  the  speaker  stands,  and  can  only  be  ob- 
tained from  them.  The  effects  are,  however,  in  reality  more 
complex,  although  they  are  produced  under  analogous  condi- 
tions, and  we  shall  have  more  to  say  about  them  when  we 
come  to  speak  of  the  experiments  made  with  the  telephone. 
It  must,  meanwhile,  be  observed  that,  for  the  reproduction  of 
speech,  it  is  not  necessary  that  the  magnetic  core  should  be  of 
soft  iron,  since  the  vibratory  effects  may  follow  from  differen- 
tial as  well  as  from  direct  magnetization. 


BELL   TELEPHONE.  63 

ORDINARY  ARRANGEMENT   OF  THE  BELL  TELEPHONE. 
The  arrangement  most  generally  adopted  for  the  telephone 
the  one  represented  in  Fig.  21.     It  consists  of  a  kind  of  cir- 


FiQ.  21. 


cular  wooden  box,  fitted  to  the  extremity  of  a  handle,  M,  which 
is  also  of  wood,  and  contains  the  magnetic  bar,  N  S.  This 
bar  is  fixed  by  means  of  a  screw,  t,  and  is  so  arranged  as  to  be 
moved  forward  and  backward  by  tightening  or  loosening  the 
screw,  a  condition  necessary  in  order  to  regulate  the  instru- 
ment. At  the  free  extremity  of  the  bar  the  magnetic  coil  B  is 
fixed ;  this  must,  according  to  MM.  Pollard  and  Gamier,  be 
made  of  wire  No.  42,  so  as  to  present  a  considerable  number  of 
spirals.  The  ends  of  this  coil  generally  terminate  at  the  lower 
end  of  the  handle  in  two  copper  rods,  /,  /,  which  traverse  its 
length,  and  are  fastened  to  two  binding  -  screws,  I,  I',  where 
the  line  wires,  C,  C,  are  fixed.  In  the  instruments  made  by  M. 
Breguet  there  are,  however,  no  binding-screws,  but  a  little  twist, 
made  of  two  flexible  wires  covered  with  gutta-percha  and  silk, 
is  fastened  to  the  two  rods.  A  wooden  cap  is  screwed  to  the 
end  of  the  handle,  and  the  twist  passes  through  a  hole  made  in 
this  cap,  so  that  there  is  no  inconvenience  in  working  the  in- 
strument. By  laying  hold  of  the  ends  of  the  wire  twist  with 
pliers  it  is  possible  to  join  them  to  the  circuit.  This  instru- 
ment is  represented  in  Fig.  22. 


64  THE    TELEPHONE. 

By  another  arrangement,  the  wires  of  the  coil  end  immedi- 
ately in  the  binding-screws  which  are  placed  below  the  wooden 
box,  but  this  arrangement  is  inconvenient. 


FIG.  22. 


Above  the  pole  of  the  magnetic  bar  is  placed  the  iron  vibra- 
ting plate,  L  L,  which  is  coated  either  with  black  or  yellow 
varnish,  with  tin  or  blue  oxide,  but  which  must  always  be  very 
thin.  This  plate  is  in  the  form  of  a  disk,  and  by  its  rim,  resting 


BREGUET   TELEPHONE.  65 

on  a  caoutchouc  ring,  it  is  firmly  fixed  to  the  circular  edges  of 
the  wooden  box,  which  is  for  this  purpose  made  in  two  pieces. 
These  pieces  are  adjusted  to  each  other,  either  by  screws  or  by 
spirals  cut  in  half  the  thickness  of  the  wood.  This  disk  ought 
to  be  as  near  as  possible  to  the  polar  end  of  the  magnet,  yet 
not  so  near  as  to  produce  contact  between  the  two  by  the  vi- 
brations of  the  voice.  Finally,  the  mouth-piece,  R  R'  (Fig.  21), 
which  is  in  form  of  a  wide  funnel,  terminates  the  upper  part  of 
the  box,  and  should  be  so  arranged  as  to  leave  a  certain  space 
between  the  disk  and  the  edges  of  the  hole  V,  which  is  open 
in  its  centre.  The  size  of  the  box  should  be  so  calculated  as  to 
permit  of  its  acting  as  a  sounding-box,  without,  however,  pro- 
voking echoes  and  a  confusion  of  sounds. 

AVhen  the  instrument  is  properly  made,  it  will  produce  very 
marked  effects ;  and  M.  Pollard,  one  of  the  first  Frenchmen  to 
take  up  the  study  of  telephones,  has  written  as  follows  on  the 
subject : 

"  The  instrument  which  I  have  prepared  gives  results  which 
are  truly  astonishing.  In  the  first  place,  when  considering  the 
resistance,  the  introduction  into  the  circuit  of  five  or  six  per- 
sons does  not  sensibly  diminish  the  intensity  of  sounds.  On 
putting  an  instrument  to  each  ear,  the  sensation  is  precisely 
the  same  as  if  the  correspondent  were  speaking  some  yards 
behind.  The  intensity,  the  clearness,  the  purity  of  tone  are 
irreproachable. 

"  I  can  speak  to  my  colleague  in  quite  an  undertone,  scarce- 
ly breathing,  as  I  may  say,  and  persons  placed  within  two 
yards  of  me  will  be  unable  to  catch  a  single  word  of  our  con- 
versation. 

"  On  the  part  of  the  receiver,  if  any  one  raises  his  voice  to 
call  me,  I  hear  the  call  in  all  parts  of  my  office,  at  least  when 
silence  prevails  there ;  at  any  rate,  when  I  am  seated  at  my 
table  with  the  instrument  some  yards  off,  I  can  always  hear 
the  call.  In  order  to  increase  the  intensity  of  sound,  I  fitted 


66  THE    TELEPHONE. 

the  mouth-piece  with  a  copper  horn  of  conical  shape,  and  un- 
der these  conditions  words  spoken  in  my  bureau  two  or  three 
yards  from  the  mouth-piece  can  be  heard  at  the  other  end  of 
the  line ;  from  my  station,  a  little  more  than  a  yard  from  the 
tube,  I  can  hear  and  speak  to  my  colleague  without  effort." 

In  using  the  ordinary  Bell  telephone,  it  is  necessary  to  speak 
distinctly  before  the  mouth -piece  of  the  telephone  which  is 
handled,  while  the  listener  placed  at  the  corresponding  station 
keeps  the  mouth-piece  of  the  receiver  to  his  ear.  These  two 


FIG.  23. 

instruments  form  a  closed  circuit  with  the  two  wires  which 
connect  them,  but  one  is  enough  to  make  the  transmission  per- 
fect, if  care  is  taken  to  place  both  instruments  in  connection 
with  the  earth,  which  thus  takes  the  place  of  the  second  wire. 
M.  Bourbouze  asserts  that  the  intensity  of  sound  in  the  tele- 
phone is  much  increased  by  employing  this  expedient,  but  we 
believe  that  this  increase  depends  upon  the  conditions  of  the 
circuit,  although  he  asserts  that  the  fact  can  be  proved  in  a 
circuit  not  exceeding  eighty  yards. 


WILMOT'S  EXPERIMENTS.  07 

For  practical  purposes  it  is  necessary  to  have  two  telephones 
at  each  station,  so  as  to  hold  one  to  the  ear  while  speaking 
through  the  other,  as  in  Fig.  23.  It  is  also  much  more  easy  to 
hear  with  a  telephone  applied  to  each  ear,  in  which  case  they 
are  held  as  in  Fig.  24.  In  order  not  to  fatigue  the  arms,  an  ar- 
rangement has  been  made  by  which  they  are  held  before  the 
ears  by  a  strap  and  spring  which  goes  round  the  head. 

The  sending  power  of  the  telephone  varies  with  different 
voices.  Mr.  Preece  asserts  that  shouting  has  no  effect,  and 


PIG.  24. 

that,  in  order  to  obtain  a  favorable  result,  the  intonation  must 
be  clear,  the  articulation  distinct,  and  the  sounds  emitted  must 
resemble  musical  sounds  as  much  as  possible. 

Mr.  Wilmot,  one  of  the  electricians  employed  by  the  Post- 
office,  says  that  he  has  been  able  to  make  himself  heard  on 
circuits  through  which  no  other  voices  were  audible.  The 
vowel  sounds  are  most  readily  transmitted,  and  among  other 
otters  c,gj,k,fmd  q  are  always  repeated  more  imperfectly. 
The  ear  requires  practice,  and  the  faculty  of  hearing  varies  in 


68  THE    TELEPHONE. 

a  surprising  degree  in  different  people.  Singing  is  very  dis- 
tinctly heard,  as  well  as  wind-instruments,  especially  the  cor- 
net-a -piston,  which,  when  played  in  London,  was  heard  by 
thousands  of  people  in  the  Corn  Exchange  at  Basingstoke. 

According  to  Mr.  Hollo  Russell,  it  is  not  necessary  to  isolate 
the  circuit  of  a  telephone  when  the  distance  is  relatively  slight ; 
thus,  with  a  circuit  of  about  430  yards,  it  is  possible  to  use  a 
simple  copper  wire,  laid  on  the  grass,  without  destroying  the 
telephonic  transmission  from  a  small  musical-box,  as  long  as 
the  two  wires  do  not  touch  each  other.  Transmission  took 
place,  even  when  the  circuit  was  buried  in  moist  earth  for  a 
length  of  thirty-five  yards,  or  immersed  in  a  well  for  a  length 
of  forty-eight  yards.  The  words  transmitted  under  such  con- 
ditions did  not  differ  from  those  transmitted  by  an  isolated 
circuit. 

The  telephone  may  be  heard  at  the  same  moment  by  several 
listeners,  either  by  connecting  the  wires  which  unite  the  tele- 
phones in  correspondence  (near  the  receiving  telephone)  with 
branch  wires  of  other  telephones,  which  may  be  done  up  to 
the  number  of  five  or  six,  in  short  circuits ;  or  by  means  of 
a  little  sounding-box  closed  by  two  thin  membranes,  one  of 
which  is  fixed  on  the  vibrating  disk.  When  a  certain  num- 
ber of  acoustic  tubes  are  connected  with  the  membrane,  Mr. 
M'Kendrick  asserts  that  several  people  can  hear  distinctly. 

Telephones  may  also  transmit  speech  to  different  stations 
simultaneously,  by  inserting  them  on  the  same  circuit,  and  ex- 
periments made  at  New  York  showed  that  five  instruments 
placed  in  different  parts  of  the  same  telegraphic  line  could  be 
made  to  speak  in  this  way.  In  the  telephonic  experiments 
made  on  the  canal  lines  in  the  department  of  the  Yonne,  it 
was  ascertained  that  on  a  wire  seven  miles  and  a  half  in  length, 
on  which  several  telephones  were  placed  at  varying  distances, 
three  or  four  persons  were  able  to  converse  with  each  other 
through  the  telephones,  and  each  could  hear  what  the  other  was 


EXPERIMENTS    AT    CHERBOURG.  69 

saying.  The  questions  and  answers  could  be  understood,  even 
in  crossing.  It  was  also  possible,  by  placing  a  telephone  on  a 
second  wire,  a  little  over  five  miles  in  length,  and  half  a  yard 
distant  from  the  other,  to  hear  the  conversation  exchanged  on 
the  first  wire  by  following  it  to  a  distance  not  exceeding  a 
mile  and  a  quarter.  Even  the  different  voices  of  the  two 
speakers  could  be  distinguished. 

Since  the  telephone  made  its  appearance  in  Europe,  several 
inventors  have  asserted  that  they  are  able  to  make  a  telephone 
speak  so  as  to  be  audible  in  all  parts  of  a  large  hall.  It  has 
been  shown  that  this  was  accomplished  by  Mr.  Bell,  and  in 
this  respect  we  do  not  see  that  those  who  have  attempted  to 
improve  the  telephone  have  attained  results  of  greater  impor- 
tance. It  is  certain  that  the  ordinary  telephone  can  emit  musi- 
cal sounds  which  become  perfectly  audible  in  a  tolerably  large 
room,  while  the  instrument  is  still  attached  to  the  wall.  We 
should  also  remember  the  results  obtained  by  MM.  Pollard  and 
Gamier  in  the  experiments  made  at  Cherbourg  to  connect  the 
mole  with  the  Prefecture  Maritime. 

The  mole  at  Cherbourg  is,  as  we  know,  a  kind  of  artificial 
island  thrown  up  before  the  town  in  order  to  make  an  anchor- 
age. The  forts  which  have  been  constructed  on  the  mole  are 
connected  by  submarine  cables  with  the  military  port  and  with 
the  Prefecture  Maritime.  On  one  occasion,  after  making  ex- 
periments in  the  prefet's  study  on  one  of  the  cables  applied  to 
a  telephone,  several  persons  were  talking  together  in  the  room, 
and  were  much  surprised  to  hear  the  bugle  sound  the  retreat, 
the  sound  appearing  to  come  from  one  part  of  the  room.  It 
was  found,  on  examination,  that  the  telephone  hung  to  the 
wall  was  occupied  with  this  performance.  On  inquiry,  it  ap- 
peared that  one  of  the  manipulators  on  the  mole  station  had 
amused  himself  by  sounding  the  bugle  before  the  telephone  on 
that  station.  The  mole  is  more  than  three  miles  from  Cher- 
bourg, and  the  Prefecture  Maritime  is  in  the  centre  of  the 


70  THE    TELEPHONE. 

town.  Yet  these  telephones  had  been  roughly  made  in  the 
dock-yard  workshops ;  and  we  have  here  another  proof  of  the 
small  amount  of  accuracy  required  for  the  successful  working 
of  these  instruments. 

Telephones  of  various  construction  on  the  Bell  model  are  to 
be  seen,  at  M.  C.  Roosevelt's,  Mr.  Bell's  agent  in  Paris,  1  Rue 
de  la  Bourse.  They  are,  for  the  most  part,  constructed  by  M. 
Breguet,  and  the  model  in  the  greatest  request,  exclusive  of 
the  one  we  have  described,  is  the  great  square  model,  with  a 
horseshoe  magnet  enclosed  in  a  flat  box,  and  a  horn  on  its  up- 
per side,  which  serves  as  a  mouth-piece.  This  system  is  repre- 
sented in  Fig.  25,  and  it  has  been  neatly  constructed  at  Boston 


FIG.  25. 


under  the  best  conditions.  In  this  new  model,  made  by  Mr. 
Gower,  the  magnet  is  composed  of  several  plates  terminated  by 
magnetic  cores  of  iron,  to  which  the  coils  are  fixed,  and  the 
whole  is  covered  with  a  thick  layer  of  paraffine.  The  sounds 
thus  reproduced  are  much  stronger  and  more  distinct.  Mr. 
Gower,  who  is  now  Mr.  Roosevelt's  partner,  has  made  consider- 
able improvements  in  the  different  forms  of  Mr.  Bell's  instru- 
ment. There  is  one  model  in  the  form  of  a  snuffbox,  in 
which  the  magnet  is  twisted  into  a  spiral,  so  as  to  maintain  its 
length  in  a  circular  form.  The  pole,  which  is  in  the  centre  of 


DIFFERENT   MODELS    OF   TELEPHONES.  71 

the  spiral,  is  furnished  with  an  iron  core,  to  which  the  induc- 
tion coil  is  fastened,  and  the  cover  of  the  snuffbox  supports 
the  vibrating  disk  as  well  as  the  mouth-piece :  this  model  is 
represented  in  Fig.  26.  In  another  model,  called  the  mirror 


FIG.  26. 


telephone,  the  preceding  arrangement  is  fitted  on  to  a  handle 
like  the  glass  of  a  portable  mirror,  and  there  is  a  mouth-piece 
on  one  of  the  lateral  faces,  so  that  the  speaker  uses  the  instru- 
ment as  if  he  were  speaking  before  a  chimney  screen. 

Mr.  Bailey  has  different  models  of  telephones  worked  by  a  bat- 
tery or  by  the  Edison  carbon,  of  which  we  shall  speak  presently, 
and  these,  as  well  as  the  telephones  by  Messrs.  Gray  and  Phelps, 
are  more  successful  in  conveying  sound  on  a  long  line  of  wire. 

DIFFERENT  ARRANGEMENTS  OF  TELEPHONES. 
The  prodigious  results  attained  with  the  Bell  telephones, 
which  were  at  first  discredited  by  many  scientific  men,  neces- 
sarily provoked,  as  soon  as  their  authenticity  was  proved,  in- 
numerable researches  on  the  part  of  inventors,  and  even  of 
those  who  were  originally  the  most  incredulous.  A  host  of 
improvements  and  modifications  have  consequently  been  sug- 


72  THE    TELEPHONE. 

gested,  which  are  evidently  not  without  interest,  and  must  now 
be  considered  by  us. 

BATTEKY  TELEPHONES. 

The  Edison  Telephone. — One  of  the  earliest  and  most  inter- 
esting improvements  made  in  the  Bell  telephone  is  that  intro- 
duced by  Mr.  Edison  in  the  early  part  of  the  year  1876.  This 
system  is  indeed  more  complicated  than  the  one  we  have  just 
considered,  since  it  requires  a  battery,  and  the  sending  instru- 
ment differs  from  the  receiving  instrument;  but  it  is  less  apt 
to  be  affected  by  external  causes,  and  transmits  sound  to  a 
greater  distance. 

The  Edison  telephone,  like  Mr.  Gray's,  which  we  have  al- 
ready had  occasion  to  mention,  is  based  upon  the  action  of 
undulatory  currents,  determined  by  the  variations  in  the  re- 
sistance of  a  conductor  of  moderate  conducting  power,  which 
is  inserted  in  the  circuit,  and  the  vibrations  of  a  diaphragm  be- 
fore which  the  speaker  stands  react  upon  it.  Only,  instead  of 
employing  a  liquid  conductor,  which  is  practically  useless,  Mr. 
Edison  has  attempted  to  use  semi -conducting  solid  bodies. 
Those  which  were  most  suitable  from  this  point  of  view  were 
graphite  and  carbon,  especially  the  carbon  extracted  from  com- 
pressed lamp-black.  When  these  substances  are  introduced 
into  a  circuit  between  two  conducting  plates,  one  of  which  is 
movable,  they  are  capable  of  modifying  the  resistance  of  the 
circuit  almost  in  the  same  proportion  as  the  pressure  exerted 
upon  them  by  the  movable  plate,1  and  it  was  seen  that,  in  or- 

1  This  property  has  long  been  known,  but  not  applied.  In  1856,  in  the 
second  edition  of  my  Expose  des  applications  d  Electridte,  I  pointed  them 
out  in  speaking  of  the  contact-breakers.  I  also  spoke  of  them  in  a  paper 
on  electro-magnets  (published  in  the  Annales  telegraphiques,  1865),  and  in 
several  articles  laid  before  the  Academic  des  Scietices  in  1872  and  1875  on 
the  conductivity  of  filings  and  conducting  powders.  M.  Clerac,  in  1865, 
also  used  them  to  obtain  variable  resistances. 


EDISOX   TELEPHONE. 


der  to  obtain  the  undulatory  currents  necessary  for  the  pro- 
duction of  articulate  sounds,  it  was  enough  to  introduce  a  disk 
of  plumbago  or  of  lamp-black  between  the  vibrating  plate  of  a 
telephone  and  a  platinum  plate  placed  in  connection  with  the 
battery.  When  the  telephone  disk  is  placed  in  circuit,  its  vi- 
brations before  the  disk  of  carbon  produce  a  series  of  increas- 
ing and  decreasing  pressures,  thus  causing  corresponding  ef- 
fects in  the  intensity  of  the  transmitted  current,  and  these 
effects  react  in  an  analogous  manner  on  the  undulatory  cur- 
rents determined  by  induction  in  the  Bell  system.  In  order 
to  obtain  good  results,  however,  several  accessory  arrangements 
were  necessary,  and  we  represent  in  Fig.  27  one  of  the  arrange- 
ments made  in  this  part 
of  Mr.  Edison's  telephon- 
ic system. 

In  this  figure  a  sec- 
tion of  the  instrument 
is  given,  and  its  form 
greatly  resembles  that 
of  Bell.  L  L  is  the  vi- 
brating disk ;  0'  0,  the 
mouth -piece;  M,  the 
opening  to  the  mouth- 
piece ;  N  N  N,  the  case 
for  the  instrument, 
which  is,  like  the  mouth- 
piece, made  of  ebonite, 
and  below  the  disk  it 
presents  a  rather  large 
cavity,  and  a  tubular  hole 
which  is  scooped  in  the 
handle.  In  its  upper  part  this  tube  terminates  in  a  cylindrical 
rim,  furnished  with  a  worm  on  which  is  screwed  a  little  rod  with 
a  ridge  on  its  inner  side,  and  the  rheostatic  system  is  placed 

4 


74  THE    TELEPHONE. 

within  this  tube.  The  system  consists,  first,  of  a  piston,  E,  fitted 
to  the  end  of  a  long  screw,  E  F,  and  the  turning  of  the  button 
will  move  the  piston  up  or  down  within  a  certain  limit.  Above 
this  piston  there  is  fitted  a  very  thin  platinum  plate,  A,  con- 
nected by  a  flexible  chain  and  a  wire  with  a  binding-screw,  P'. 
Another  plate,  B,  exactly  similar,  is  connected  with  the  bind- 
ing-screw P,  and  the  carbon  disk,  C,  is  placed  between  these 
two  plates.  This  disk  is  composed  of  compressed  lamp-black 
and  petroleum,  and  its  resistance  is  one  ohm,  or  110  yards,  of 
telegraphic  wire.  Finally,  an  ebonite  disk  is  fastened  to  the 
upper  platinum  plate,  and  an  elastic  pad,  composed  of  a  piece 
of  caoutchouc  tube,  G,  and  of  a  cork  disk,  H,  is  interposed  be- 
tween the  vibrating  plate  L  L  and  the  disk  B,  in  order  that 
the  vibrations  of  the  plate  may  not  be  checked  by  the  rigid 
obstacle  formed  by  the  whole  rheostatic  system.  When  these 
different  parts  are  in  position,  the  instrument  is  regulated  by 
the  screw  F,  and  this  is  easily  done  by  screwing  or  unscrewing 
it  until  the  receiving  telephone  gives  out  its  maximum  of 
sound. 

In  another  model,  represented  in  Fig.  28,  which  has  produced 
the  best  results  in  the  distinctness  with  which  sounds  are  trans- 
mitted, the  vibrating  plate,  L  L,  is  supported  on  the  disks  of 

the  secondary  carbon 
conductor,  C,  by  means 
of  a  little  iron  cylinder, 
A,  instead  of  the  caout- 
chouc pad,  and  the 
pressure  is  regulated  by 
a  screw  placed  below  e. 
FlG'  28'  The  mouth -piece,  E,  of 

the  instrument  is  more  prominent,  and  its  opening  is  larger. 
Finally,  the  instrument,  which  is  cased  in  nickel  silver,  is  with- 
out a  handle.  The  rigid  disk,  5,  resting  on  the  first  platinum 
plate,  p,  is  of  aluminium  instead  of  ebonite. 


ANOTHER    EDISON   TELEPHONE. 


75 


The  receiving  telephone  somewhat  resembles  that  of  Mr. 
Bell,  yet  it  presents  some  differences  which  can  be  understood 
from  the  examination  of  Fig. 
29.  The  magnet,  N  S,  is  C 
horseshoe  in  form,  and  the 
magnetizing  coil,  E,  only  cov- 
ers one  of  the  poles,  N :  this 
pole  is  precisely  in  the  centre 
of  the  vibrating  plate,  L  L, 
while  the  second  pole  is  near 
the  edge  of  this  plate.  The 
size  of  the  plate  itself  is  con- 
siderably reduced:  its  super- 
ficies is  about  the  same  as 
that  of  a  five-franc  piece,  and 
it  is  enclosed  in  a  kind  of 
circular  groove,  which  keeps 
it  in  a  definite  position.  In 
consequence  of  this  arrange- 
ment, the  handle  of  the  in- 
strument is  of  solid  wood, 
and  the  vacant  space  for  the  electro-magnetic  system  is  some- 
what larger  than  in  the  Bell  model ;  but  an  arrangement  is 
made  for  subduing  the  echo,  and  there  is  a  kind  of  sounding- 
box  to  magnify  the  sound.  It  is  evident  that  the  relation 
which  the  electro-magnetic  system  bears  to  the  vibrating  disk 
must  increase  the  sensitiveness  of  the  instrument;  for  as  the 
pole  S  is  in  close  contact  with  the  disk,  L  L,  the  latter  is  polar- 
ized, and  becomes  more  susceptible  to  the  magnetic  influence 
of  the  second  pole,  N,  which  is  separated  from  it  by  an  interval 
not  exceeding  the  thickness  of  a  sheet  of  coarse  paper.  In  Mr. 
Edison's  two  instruments,  the  receiver  and  sender,  the  upper 
part,  C  C,  corresponding  to  the  vibrating  disk,  instead  of  being 
fixed  by  screws  to  the  handle,  is  screwed  on  to  the  handle  it- 


FIG.  29. 


76  THE    TELEPHONE. 

self,  which  makes  it  much  more  easy  to  dismount  the  instru- 
ment. 

Mr.  Edison  has  varied  the  form  of  his  instruments  in  many 
ways,  and  their  cases  have  of  late  been  made  of  metal  with  a 
funnel-shaped  mouth-piece  of  ebonite. 

When  Mr.  Edison  had  ascertained,  as  indeed  Mr.  Elisha  Gray 
had  done  before  him,  that  induced  currents  are  more  favorable 
to  telephonic  transmissions  than  voltaic  currents,  he  transformed 
the  currents  from  the  battery  which  passed  through  his  sender 
into  induced  currents  by  making  them  pass  through  the  pri- 
mary circuit  of  a  carefully  insulated  induction  coil ;  the  line 
wire  was  then  put  into  communication  with  the  secondary  wire 
of  the  coil.  We  shall  afterward  describe  some  experiments 
which  show  the  advantages  of  this  combination :  for  the  pres- 
ent we  can  only  point  out  the  fact,  for  it  is  now  an  integral 
quality  of  almost  all  the  systems  of  battery  telephones. 

Edison's  Chemical  Telephone. — The  curious  and  really  useful 
effects  produced  by  Mr.  Edison  with  his  electro  -  motograph 
prompted,  about  the  beginning  of  the  year  1877,  his  idea  of 
applying  the  principle  of  this  instrument  to  the  telephone  for 
the  reproduction  of  transmitted  sounds ;  and  he  obtained  such 
interesting  results  that  the  author  of  an  article  on  telephones, 
published  in  the  Telegraphic  Journal,  August  15th,  1877,  put 
forward  this  invention  as  one  of  the  finest  of  the  nineteenth 
century.  It  certainly  appears  to  have  given  birth  to  the  pho- 
nograph, which  has  lately  become  famous,  and  has  so  much 
astonished  men  of  science. 

To  understand  the  principle  of  this  telephone,  we  must  give 
some  account  of  Mr.  Edison's  electro-motograph,  discovered  in 
1872.  This  instrument  is  based  upon  the  principle  that  if  a 
sheet  of  paper,  prepared  with  a  solution  of  hydrate  of  potash, 
is  fastened  on  a  metallic  plate  which  is  united  to  the  positive 
pole  of  a  battery,  and  if  a  point  of  lead  or  platinum  connected 
with  the  negative  pole  is  moved  about  the  paper,  the  friction 


TELEPHONIC    RECEIVER.  77 

which  this  point  encounters  ceases  after  the  passage  of  the  cur- 
rent, and  it  is  then  able  to  slide  as  if  upon  a  mirror  until  the 
current  is  interrupted.  Now,  as  this  reaction  may  be  effected 
instantaneously  under  the  influence  of  extremely  weak  currents, 
the  mechanical  effects  produced  by  these  alternations  of  arrest 
and  motion  may,  by  a  suitable  arrangement  of  the  instrument, 
determine  vibrations  in  correspondence  with  the  interruptions 
of  current  produced  by  the  transmitter. 

In  this  system  the  telephonic  receiver  consists  of  a  resonator 
and  a  drum  mounted  on  an  axis  and  turned  by  a  winch.  A 
paper  band,  wound  upon  a  reel,  passes  over  the  drum,  of  which 
the  surface  is  rough,  and  a  point  tipped  with  platinum,  and  fit- 
ted to  the  end  of  a  spring  which  is  fixed  in  the  centre  of  the 
resonator,  presses  strongly  on  the  paper.  f  The  current  from 
the  battery,  first  directed  on  the  spring,  passes  by  the  platinum 
point  through  the  chemical  paper,  and  returns  by  the  drum  to 
the  battery.  On  turning  the  winch,  the  paper  moves  forward, 
and  the  normal  friction  which  is  produced  between  the  paper 
and  the  platinum  point  pushes  the  point  forward,  while  pro- 
ducing, by  means  of  the  spring,  a  tension  on  one  side  of  the 
resonator;  but  since  the  friction  ceases  at  each  passage  of  the 
current  through  the  paper,  the  spring  is  no  longer  drawn  out, 
and  the  resonator  returns  to  its  normal  position.  Since  this 
double  effect  is  produced  by  each  vibration  made  in  the  sender, 
a  series  of  vibrations  takes  place  in  the  resonator,  repeating 
those  of  the  sender,  and  consequently  the  musical  sounds 
which  affected  the  sender  are  reproduced  to  a  certain  extent. 
According  to  the  American  journals,  the  results  produced  by 
this  instrument  are  astonishing:  the  weakest  currents,  which 
would  have  no  effect  on  an  electro-magnet,  become  perfectly  effi- 
cacious in  this  way.  The  instrument  can  even  reproduce  with 
great  intensity  the  highest  notes  of  the  human  voice,  notes 
which  can  hardly  be  distinguished  by  the  use  of  electro-magnets. 

The  sender  nearly  resembles  the  one  we  have  previously  de- 


78  THE    TELEPHONE. 

scribed,  except  that,  when  it  is  used  for  musical  sounds,  a  plati- 
num point  is  employed  instead  of  the  disk  of  carbon,  and  it 
ought  not  to  be  in  constant  contact  with  the  vibrating  plate. 
According  to  the  Telegraphic  Journal,  it  consists  simply  of  a 
long  tube,  two  inches  in  diameter,  having  one  end  covered  with 
a  diaphragm  formed  of  a  thin  sheet  of  copper,  and  kept  in  its 
place  by  an  elastic  ring.  A  small  platinum  disk  is  riveted  to 
the  centre' of  the  copper  diaphragm,  and  a  point  of  the  same 
metal,  fitted  with  a  firm  support,  is  adjusted  before  the  disk. 
When  the  singer  stands  before  the  diaphragm,  its  vibration 
causes  it  to  touch  the  platinum  point,  and  produces  the  num- 
ber of  breaks  in  the  current  which  corresponds  to  the  vibration 
of  the  notes  uttered. 

The  experiments  lately  made  in  America,  in  order  to  decide 
on  the  merits  of  various  telephonic  systems,  show  that  Mr. 
Edison's  telephone  gives  the  best  results.  The  Telegraphic 
Journal,  May  1st,  1878,  states  that  on  April  2d  Mr.  Edison's 
carbon  telephone  was  tested  between  New  York  and  Phila- 
delphia on  one  of  the  numerous  lines  of  the  Western  Union. 
The  length  of  the  line  was  106  miles,  and  ran  parallel  to  other 
wires  almost  throughout  its  length.  The  effects  of  induction 
caused  by  telegraphic  transmissions  through  the  adjacent  wires 
were  enough  to  make  speech  inaudible  through  the  other  tele- 
phones, but  they  had  no  influence  on  Edison's  telephone,  which 
was  worked  With  a  battery  of  two  cells  and  a  small  induction 
coil,  and  Messrs.  Batchelor,  Phelps,  and  Edison  were  able  to 
converse  with  ease.  Mr.  Phelps's  magnetic  telephone,  which  is 
considered  to  be  the  most  powerful  of  its  kind,  did  not  afford 
such  good  results. 

In  the  experiments  made  between  the  Paris  Exhibition  build- 
ing and  Versailles,  the  jury  commission  was  able  to  ascertain 
that  the  results  were  equally  favorable. 

Telephones  by  Colonel  Navez. — Colonel  Navez,  of  the  Bel- 
gian Artillery,  inventor  of  the  well-known  balistic  chronograph, 


NAVEZ   TELEPHONE.  79 

has  endeavored  to  improve  the  Edison  telephone  by  employ- 
ing several  disks  of  carbon  instead  of  one.  He  considers  that 
the  variations  of  electric  resistance  produced  by  carbon  disks 
under  the  influence  of  unequal  pressure  depend  chiefly  on  their 
surface  of  contact,  and  he  consequently  believes  that  the  more 
these  surfaces  are  multiplied,  the  greater  the  differences  in 
question  will  be,  just  as  it  happens  when  light  is  polarized 
through  ice.  He  adds  that  these  disks  act  well  by  their  sur- 
faces of  contact,  since,  if  they  are  separated  by  copper  disks, 
the  speech  reproduced  ceases  to  be  articulate.1 

I  am  not  surprised  to  learn  that  Colonel  Navez  has  found  a 
limit  to  the  number  of  carbon  disks,  for  the  reproduction  of 
speech  in  this  system  is  due  both  to  the  greatness  of  the  dif- 
ferences of  resistance  in  the  circuit  and  to  the  intensity  of  the 
transmitted  current.  If,  therefore,  the  instrument's  sensitive- 
ness to  articulate  sounds  is  increased  by  increasing  the  number 
of  imperfect  contacts  in  the  circuit,  the  intensity  of  the  trans- 
mitted sounds  is  diminished,  and  thus  sounds  lose  their  power. 
There  is  consequently  a  limit  to  be  observed  in  the  number  of 
carbon  disks  placed  upon  each  other;  and  it  depends  on  the 
nature  of  the  imperfect  contacts  which  are  employed,  and  on 
the  tension  of  the  electric  generator. 

In  order  to  stop  the  unpleasant  musical  vibrations  which  ac- 
company telephonic  transmissions,  Colonel  Navez  employs  for 
the  vibrating  plate  of  the  sender  a  silver-plated  copper  disk, 
and  for  the  vibrating  plate  of  the  receiver  an  iron  disk  lined 
with  brass  and  soldered  together.  He  also  employs  caout- 
chouc tubes  with  mouth-pieces  and  ear-tubes  for  the  transmis- 
sion and  reception  of  sound,  and  these  instruments  are  placed 
level  on  a  table.  For  this  purpose  the  magnetized  bar  of  the 

1  In  1865  I  was  able  to  verify  this  observation  when  tightening  the 
spirals  of  an  electro-magnet  on  a  naked  wire.  The  greater  the  number 
of  spirals  under  pressure,  the  more  definite  were  the  differences  of  resist- 
ance in  the  magnetizing  helix. 


80 


THE    TELEPHONE. 


receiving  telephone  is  replaced  by  two  horizontal  magnets,  act- 
ing through  a  pole  of  the  same  nature  on  a  little  iron  core 
which  carries  the  coil,  and  which  is  placed  vertically  between 
the  two  magnets.  He  necessarily  makes  use  of  a  small  Ruhm- 
korff  coil  to  transform  the  electricity  of  the  battery  into  in- 
duced electricity. 


FIG.  30. 

Figs.  30  and  31  represent  the  two  parts  of  this  telephonic 
system.  The  carbon  battery  is  in  C  (Fig.  30),  the  vibrating 
disk  in  L  L,  and  the  mouth -piece,  E,  fitted  to  a  caoutchouc 
tube,  T  E,  corresponds  at  the  lower  end  to  the  vibrating  disk. 
The  carbon  battery  is  placed  in  metallic  contact  with  the  cir- 
cuit by  a  platinum  rod,  E  C,  and  the  vibrating  disk  also  com- 
municates with  the  circuit  through  a  binding-screw.  In  the 
receiving  telephone  (Fig.  31)  the  upper  part  is  arranged  much 
as  in  the  ordinary  telephones,  except  that,  instead  of  a  mouth- 


POLLABD   AND   GAKXIER   TELEPHONE. 


81 


piece,  the  instrument  is  fitted  with  an  ear-tube,  T  O.  The  two 
horseshoe  magnets,  A  A,  which  communicate  a  uniform  polar- 
ity to  the  iron  core,  N,  support  the  induction  coil  B.  The 
two  terminals  of  this  receiver  are  connected  with  the  supple- 
mentary wire  of  the  induction  coil,  and  the  two  terminals  of 
the  sender  are  connected  with  the  two  ends  of  the  primary  of 
this  coil,  and  with  the  battery  which  is  inserted  in  the  circuit 
near  this  instrument. 

o 


-I/./,     '''' 


FIG.  31. 


The  Pollard  and  Gamier  Telephones.  —  The  battery  tele- 
phone made  by  MM.  Pollard  and  Gamier  differs  from  the 
foregoing  in  this  particular :  it  simply  employs  two  points  of 
graphite,  mounted  in  metallic  porte-crayons,  and  these  points 
are  directly  applied  against  the  vibrating  plate  with  a"  pressure 
which  must  be  regulated.  Fig.  32  represents  the  arrangement 
adopted,  which,  however,  may  be  infinitely  varied. 

L  L  is  the  vibrating  tin  plate,  above  which  is  the  mouth- 
4* 


82  THE    TELEPHONE. 

piece  E,  and  P,  P'  are  the  two  graphite  points,  with  their  porte- 

crayons.  There  is  a  screw  on 
the  lower  part  of  the  porte-cray- 
ons  which  is  fixed  in  a  hole 
pierced  in  a  metallic  plate,  C  C, 
and  by  this  means  the  pressure 
of  the  pencils  against  the  disk 
L  L  can  be  regulated.  The  me- 
tallic plate  C  C  is  made  in  two 

pieces,  placed  side  by  side,  but  insulated  from  each  other,  so 
that  they  may  be  placed  in  communication  with  a  cylindrical 
commutator,  and  by  its  means  the  circuit  can  be  arranged  in 
different  ways.  Since  the  commutator  consists  of  five  sheets, 
the  transition  from  one  combination  to  another  is  instantane- 
ous, and  these  combinations  are  as  follows : 

1.  The  current  enters  by  the  pencil  P,  passes  into  the  plate, 
and  so  to  line. 

2.  The  current  enters  by  the  pencil  P',  passes  into  the  plate, 
and  so  to  line. 

3.  The  current  comes  simultaneously  by  the  two  pencils,  P 
and  P',  goes  into  the  plate,  and  thence  to  line. 

4.  The  current  comes  by  the  pencil  P,  goes  thence  to  the 
plate,  then  into  the  pencil  P',  and  so  to  line. 

By  this  means  there  are  two  elements  of  combination,  which 
may  be  employed  separately,  or  by  coupling  them  for  tension 
or  quantity. 

When  the  pencils  are  properly  regulated  and  give  a  regular 
transmission  of  equal  intensity,  the  effects  produced  in  the  tran- 
sition from  one  combination  to  another  may  be  easily  studied, 
and  it  has  been  ascertained :  first,  that  in  a  short  circuit  there 
is  no  appreciable  change,  whatever  be  the  combination  employ- 
ed ;  secondly,  that  when  the  circuit  is  long,  or  of  great  resist- 
ance, the  tension  arrangement  is  the  best,  and  this  in  propop 
tion  to  the  length  of  the  line. 


HELLESEN'S  REACTION  TELEPHONE.  83 

This  telephonic  system,  like  the  two  preceding  ones,  requires 
an  inducing  machine  to  transform  voltaic  into  induced  cur- 
rents :  we  shall  presently  speak  of  this  important  accessory  of 
these  instruments. 

Besides  this  arrangement,  MM.  Pollard  and  Gamier  have 
employed  the  one  we  have  represented  in  Fig.  5,  which  has 
given  better  results.  We  shall  see  presently  that  it  can  be 
used  as  the  receiving  organ  of  sounds.  In  each  case  the  two 
carbons  must  be  placed  in  contact,  and  subjected  to  a  certain 
initial  pressure,  which  should  be  regulated  by  the  screw  fitted 
to  the  support  of  the  lower  carbon. 

As  for  the  receiving  telephone,  the  arrangement  adopted  by 
MM.  Pollard  and  Gamier  is  the  same  as  Bell's,  except  that  they 
employ  tin  plates  and  helices  of,  greater  resistance.  This  re- 
sistance ranges,  in  fact,  from  100  to  125  miles.  "We  have  al- 
ways held,"  these  gentlemen  say,  "  that  whatever  may  be  the 
resistance  of  the  outer  circuit,  there  is  an  advantage  in  increas- 
ing the  number  of  spirals,  even  when  using  wire  No.  42,  which 
is  the  one  we  prefer." 

M.  Hellesen's  Reaction  Telephone.  —  M.  Hellesen  believed 
that  the  vibrations  produced  by  the  voice  on  the  carbon  of  a 
telephonic  sender  would  be  magnified  if  the  movable  part  of 
the  rheotome  were  subjected  to  an  electro-magnetic  action  re- 
sulting from  the  vibrations  themselves,  and  he  has  contrived  a 
sender,  which  is  based  on  the  principle  shown  in  Fig.  33,  and 
which  has  the  merit  of  forming  in  itself  the  inducing  appara- 
tus intended  to  transform  the  voltaic  currents  employed.  This 
instrument  is  composed  of  a  vertical  iron  tube,  supported  on  a 
magnetic  bar,  N  S,  and  surrounded  by  a  magnetizing  coil,  B  B, 
above  which  is  fixed  an  inducing  helix  of  fine  wire,  I  I,  com- 
municating with  the  circuit.  Within  the  tube  there  is  a  lead 
pencil,  C,  held  by  a  porte-crayon,  which  can  be  raised  or  lower- 
ed by  means  of  a  screw,  V,  fixed  below  the  magnetic  bar. 
Finally,  above  this  pencil  there  is  an  iron  vibrating  plate,  L  L, 


84 


THE    TELEPHONE. 


with  a  platinum  point  in  communication  with  the  battery  in 
its  centre ;  the  local  circuit  communicates  with  the  pencil  by 
means  of  the  magnetizing  helix  B,  and  for  this  purpose  one 
end  is  soldered  to  the  iron  tube. 


FIG.  33. 

From  this  arrangement  it  follows  that  the  vibrations  of  the 
plate  L  L,  at  the  moment  when  it  comes  nearest  to  the  pencil, 
tend  to  become  greater  in  consequence  of  the  attractive  force 
exerted  on  the  plate ;  and  as  the  pressure  of  the  lead  pencil  is 
increased,  it  increases  the  differences  of  resistance  which  result 
from  it,  and  consequently  causes  greater  variations  in  the  in- 
tensity of  the  transmitted  currents. 

Reaction  Telephone  of  Messrs.  Thomson  and  Houston. — The 
telephonic  arrangement  we  have  described  has  lately  been 
adopted  by  Mr.  Elihu  Thomson  and  Mr.  Edwin  J.  Houston, 
who,  on  June  21st,  1878,  two  months  after  M.  Hellesen  ex- 
plained his  system  to  me,1  published  an  article  in  The  English 

1  M.  Hellesen  communicated  the  plan  of  his  instrument  to  me  on  May 
3d,  1878,  and  his  experiments  were  made  in  Copenhagen  three  weeks  ear- 
lier. 


THOMSON   AND    HOUSTON   TELEPHONE.  85 

Mechanic  and  World  of  Science  about  an  instrument  very  sim- 
ilar to  that  of  M.  Hellesen. 

In  their  instrument  the  current,  which  passes  through  a 
body  of  moderately  conducting  capacity,  acts  on  an  electro- 
magnet provided  with  an  induction  coil,  and  this  electro-mag- 
net reacts  on  the  diaphragm,  in  order  to  increase  the  range  of 
its  vibrations,  and  to  create  at  the  same  moment  two  electric 
actions  in  the  same  direction :  the  only  difference  lies  in  the 
arrangement  of  the  contact  of  this  indifferent  conductor  with 
the  vibrating  plate.  Instead  of  a  simple  contact  effected  by 
pressure  between  this  plate  and  a  carbon  pencil,  a  fragment  of 
the  same  substance  with  a  sharpened  point  is  fixed  on  the  vi- 
bratirg  plate,  and  it  dips  into  a  drop  of  mercury  which  has 
been  poured  into  the  receptacle  made  for  it  at  the  upper  end 
of  the  electro-magnet.  In  other  respects  the  arrangement  of 
the  instrument  is  that  of  an  ordinary  telephone,  and  the  iron 
rod  of  the  electro-magnet  represents  the  magnetized  bar  of  the 
Bell  telephone.  The  inventors  assert  that  this  instrument  can 
be  used  both  as  a  sender  and  receiver,  and  it  is  in  the  follow- 
ing manner  that  it  is  worked  in  each  case : 

AVhen  the  instrument  is  transmitting,  the  morsel  of  carbon 
dips  more  or  less  into  the  mercury,  and  consequently  differ- 
ences are  produced  in  the  surfaces  of  contact,  according  to  the 
range  of  vibrations  made  by  the  plate;  the  current  varies  in 
intensity  in  proportion  to  this  range,  and  induced  currents  in 
the  induction  coil  result  from  these  variations;  the  induced 
currents  react  on  the  receiving  telephone,  as  in  Bell's  instru- 
ment, and  are  further  strengthened  by  those  which  are  pro- 
duced electrically  by  the  movement  of  the  diaphragm  before 
the  induction  coil,  and  the  iron  of  the  electro-magnet. 

When  the  instrument  is  used  as  a  receiver,  the  usual  effects 
are  displayed ;  for  since  the  iron  of  the  electro-magnet  is  mag- 
netized by  the  current,  its  conditions  are  precisely  those  of  the 
ordinary  Bell  telephone,  and  the  induced  currents  reach  it  in 


86  THE    TELEPHONE. 

the  same  manner,  only  with  greater  intensity.  Messrs.  Thom- 
son and  Houston  assert  that  their  system  has  produced  excel- 
lent results,  and  that  by  it  the  sound  of  the  voice  is  much  less 
altered  than  in  other  telephones. 

Telephones  with  Batteries  and  Liquid  Senders.  — -  We  have 
seen  that  in  1867  Mr.  Gray  conceived  the  idea  of  a  telephonic 
system  based  on  the  differences  of  resistance  effected  in  a  cir- 
cuit completed  by  a  liquid,  when  the  layer  of  liquid  interposed 
between  the  electrodes  varies  in  thickness  under  the  influence 
of  the  vibrations  of  the  telephonic  plate  which  is  in  communi- 
cation with  one  of  these  electrodes.  This  system  has  since  been 
the  subject  of  study  by  several  inventors,  among  others  by 
MM.  Richemond  and  Salet,  and  I  give  some  of  the  accounts 
which  have  been  published  respecting  their  researches. 

Another  telephone  for  the  reproduction  of  articulate  sounds, 
which  M.  Richemond  terms  the  electro-hydro  telephone,  has  been 
recently  patented  in  the  United  States.  It  resembles  that  of 
Mr.  Edison  in  some  respects ;  but  instead  of  making  use  of  car- 
bon disks  to  modify  the  resistance  of  the  circuit,  water  is  em- 
ployed, and  this  water  is  placed  in  communication  with  the  cir- 
cuit and  battery  by  means  of  two  platinum  points,  one  of  which 
is  fixed  on  the  metallic  diaphragm  which  vibrates  under  the 
influence  of  the  voice.  As  the  vibrations  of  the  diaphragm 
transport  the  point  which  is  attached  to  it  to  different  parts 
of  the  interpolar  layer  of  liquid,  they  diminish  or  increase  the 
electric  resistance  of  this  layer,  and  cause  corresponding  varia- 
tions in  the  intensity  of  the  current  traversing  the  circuit.  The 
receiving  telephone  is  of  the  usual  kind.  (See  Telegraphic 
Journal,  September  15th,  1877.) 

M.  Salet  writes :  "  I  thought  it  would  be  interesting  to  con- 
struct a  telephone  in  which  there  should  be  absolute  solidarity 
in  the  movements  of  the  two  membranes,  and  for  this  purpose 
I  have  availed  myself  of  the  great  resistance  of  liquids.  Mr. 
Bell  had  already  obtained  some  results  by  attaching  to  the  vi- 


LIQUID  TELEPHONE.  87 

brating  membrane  a  platinum  wire  communicating  with  a  bat- 
tery, and  dipping  more  or  less  into  a  metallic  vessel,  itself  con- 
nected by  the  line  with  the  receiving  telephone  and  containing 
some  acidulated  water.  I  have  substituted  for  the  platinum 
wire  a  small  aluminium  lever  supporting  a  disk  of  platinum, 
and  at  a  very  slight  distance  from  it  there  is  a  second  disk  in 
connection  with  the  line.  The  vibrations  of  the  membrane, 
tripled  or  quadrupled  in  their  range,  are  not  altered  in  form, 
thanks  to  the  small  size  and  light  weight  of  the  lever :  they 
cause  variations  in  the  thickness  of  the  liquid  layer  traversed 
by  the  current,  and  consequently  in  its  intensity,  and  these  va- 
riations cause  corresponding  differences  in  the  attractive  force 
of  the  receiving  electro-magnet.  Under  its  influence  the  re- 
ceiving membrane  executes  movements  which  are  identical  with 
those  of  the  sending  membrane.  The  sound  transmitted  is 
very  distinct,  and  its  timbre  is  perfectly  maintained — a  result 
which  might  have  been  anticipated.  The  consonants,  however, 
are  not  so  clearly  pronounced  as  those  transmitted  by  Mr.  Bell's 
instrument.  This  inconvenience  is  most  apparent  when  the 
lever  is  heavy,  and  might  easily  be  obviated.  The  electrolysis 
also  produces  a  continual  murmur,  but  this  does  not  interfere 
with  the  distinctness  of  the  sound. 

"  Since,  on  this  system,  the  voice  is  not  required  to  produce, 
but  only  to  direct,  the  electric  current  generated  by  a  battery, 
the  intensity  of  the  sound  received  might  in  theory  be  increased 
at  pleasure.  I  have,  in  fact,  been  able  to  make  the  receiver  emit 
very  powerful  sounds,  and  I  think  that  this  advantage  greatly 
counterbalances  the  necessity  of  employing  a  battery,  and  a 
somewhat  delicate  sending  instrument.  Unfortunately  it  can 
only  be  used  for  moderate  distances.  Assuming  that  any  dis- 
placement of  the  transmitting  membrane  increases  the  resist- 
ance to  a  degree  equivalent  to  five  or  six  hundred  yards  of 
wire :  if  the  line  is  five  hundred  yards  long,  the  intensity  of 
the  current  will  be  reduced  by  one-half,  and  the  receiving  mem- 


88  THE    TELEPHONE. 

brane  will  take  up  a  fresh  position,  considerably  differing  from 
the  first ;  but  if  the  line  is  three  hundred  miles  in  length,  the 
intensity  of  the  current  will  only  be  modified  by  a  thousandth 
part.  An  immense  battery  must  therefore  be  employed  in  or- 
der that  this  variation  may  be  translated  by  a  sensible  change 
in  the  position  of  the  receiving  membrane."  (See  Comptes 
Rendus  de  V Academic  des  Sciences,  February  18th,  1878.) 

M.  J.  Luvini,  in  an  article  inserted  in  Les  Mondes,  March  7th, 
1878,  has  suggested  a  system  of  rheotome  by  means  of  a  cur- 
rent, for  battery  telephones,  which,  although  complicated,  possi- 
bly offers  some  advantages,  since  it  produces  currents  alternate- 
ly reversed.  In  this  system  the  vibrating  disk  of  the  sender, 
which  should  be  in  a  vertical  position,  reacts  on  a  movable  hor- 
izontal wire,  turned  back  at  a  right  angle,  and  supporting  on 
each  of  its  branches  two  platinum  points  which  dip  into  two 
bulbs,  filled  with  a  liquid  of  moderate  conducting  capacity. 
The  two  branches  of  this  wire,  insulated  from  each  other,  are 
placed  in  communication  with  the  two  poles  of  the  battery,  and 
the  four  cups  into  which  the  platinum  wire  dips  communicate 
inversely  with  the  line  and  the  earth  by  means  of  platinum 
wires  immovably  fixed  in  the  cups.  It  follows  from  this  ar- 
rangement that,  when  the  distances  are  duly  regulated  between 
the  fixed  and  movable  wires,  two  equal  currents  will  be  opposed 
to  each  other  across  the  line  circuit  when  the  diaphragm  is  mo- 
tionless ;  but  as  soon  as  it  vibrates,  the  respective  distances  of 
the  wires  will  vary,  and  it  follows  from  this  that  there  will  be 
a  differential  current,  of  which  the  intensity  will  correspond 
with  the  extent  of  the  displacement  of  the  system,  or  with  the 
range  of  vibrations,  and  the  direction  will  vary  with  the  move- 
ments above  or  below  the  line  of  the  nodes  of  vibration.  In 
this  way  the  advantage  of  the  induced  currents  is  obtained. 

Telephones  with  a  Battery  and  Voltaic  Arcs. — In  order  to 
obtain  variations  of  resistance  of  still  greater  sensitiveness  than 
is  the  case  with  liquids  or  pulverized  substances,  the  idea  has 


VOLTAIC   ABC   TELEPHONE.  89 

been  suggested  of  employing  conductors  of  heated  gas,  and 
several  arrangements  of  battery  telephones  have  been  made  in 
which  the  circuit  was  completed  by  a  stratum  of  air,  separating 
the  vibrating  disk  from  a  platinum  point,  which  serves  to  ex- 
cite an  electric  discharge  of  high  tension.  Under  these  condi- 
tions, the  stratum  of  air  becomes  the  conductor,  and  the  inten- 
sity of  the  current  which  traverses  it  corresponds  to  its  thick- 
ness. This  problem  has  been  solved,  either  by  means  of  vol- 
taic currents  of  high  tension,  or  by  a  Ruhmkorff  coil. 

The  former  system  was  arranged  by  M.  Trouve,  and  he 
writes  as  follows  on  the  subject  in  the  journal  La  Nature  of 
April  6th,  1878:  "A  metallic  vibrating  membrane  forms  one 
of  the  poles  of  a  high-tension  battery ;  the  other  pole  is  fast- 
ened before  the  disk  by  a  micrometer  screw, which  can  be  ad- 
justed so  as  to  vary  the  distance  from  the  disk  according  to 
the  tension  of  the  battery,  but  without  ever  coming  in  contact 
with  it.  The  distance  must  not  in  any  case  exceed  that  to 
which  the  discharge  of  the  batteiy  can  extend.  Under  these 
conditions,  the  membrane  which  vibrates  under  the  influence 
of  the  waves  of  sound  has  the  effect  of  constantly  modifying 
the  distance  between  the  two  poles,  and  thus  of  continually 
varying  the  intensity  of  the  current :  consequently  the  receiv- 
ing instrument  (a  Bell  telephone,  or  telephone  with  an  electro- 
magnet) is  subjected  to  magnetic  variations,  corresponding  to 
the  variations  of  the  current  which  affect  it,  and  this  has  the 
effect  of  making  the  receiving  instrument  vibrate  at  the  same 
moment.  This  kind  of  telephonic  instrument  relies,  therefore, 
on  the  possibility  of  varying  within  wide  limits  the  resistance 
of  the  outer  circuit  of  a  high-tension  battery,  in  which  the 
poles  are  not  in  contact.  In  order  to  vary  the  conditions  of 
this  resistance,  it  is  also  possible  to  interpose  some  vapor  or 
"other  medium,  such  as  air,  or  gas  of  greater  or  less  rarity." 

M.  Trouve  thinks  that  he  was  successful  with  his  battery 
of  small  disks,  moistened  with  sulphate  of  copper  and  sulphate 


90  THE    TELEPHONE. 

of  zinc,  arranging  these  elements,  to  the  number  of  five  or  six 
hundred,  in  glass  tubes  of  small  diameter.  It  is  well  known 
that  it  is  unnecessary  for  the  elements  to  be  of  large  size  in 
order  to  obtain  tension  currents. 

M.  de  Lalagade  has  suggested  an  analogous  mode  by  em- 
ploying for  the  formation  of  the  arc  a  current  of  which  the 
tension  is  increased  by  inserting  a  strong  electro-magnet  into 
the  circuit.  This  electro-magnet  acts  on  a  Hughes  magnet  in 
order  to  produce  induction  currents  capable  of  making  the  re- 
ceiving instrument  act.  M.  de  Lalagade  says  that  a  Bunsen 
battery,  or  one  of  six  cells  with  bichromate  of  potash,  will  be 
enough  to  produce  a  continuous  voltaic  arc  between  the  vibra- 
ting plate  of  a  telephone  and  a  platinum  point  which  is  suffi- 
ciently remote  to  avoid  contact.  It  is  necessary,  however,  to 
begin  with  a  contact,  in  order  to  produce  the  formation  of  this 
arc.  In  M.  de  Lalagade's  system  the  vibrating  plate  should 
have  in  its  centre  a  small  platinum  plate,  in  order  to  obviate 
the  oxidizing  effects  of  the  spark.  The  inventor  asserts  that 
sounds  transmitted  in  this  way,  and  reproduced  in  a  telephone 
of  which  the  electro-magnetic  system  is  set  upon  a  sounding- 
box,  will  have  greater  intensity  than  the  sounds  transmitted 
by  an  ordinary  telephone,  and  the  speaker  will  appear  to  be 
close  to  the  ear. 

Mercury  Telephones. — These  systems  are  based  on  the  phys- 
ical principle  discovered  by  M.  Lippmann,  that  if  a  layer  of 
acidulated  water  is  placed  above  mercury,  and  connected  with 
it  by  an  electrode  and  wire,  every  mechanical  action  which  ex- 
erts pressure  on  the  surface  of  the  mercury,  and  alters  the 
form  of  its  meniscus,  will  cause  an  electric  reaction,  capable  of 
producing  a  current  with  a  force  which  corresponds  to  the 
mechanical  action  exerted.  Conversely,  every  electric  action 
produced  on  the  circuit  of  such  a  system  will  occasion  a  dis- 
placement of  the  meniscus,  and  consequently  its  movement, 
which  will  be  more  marked  in  proportion  to  the  smallness  of 


MERCURY  TELEPHONE. 


91 


the  tube  in  which  the  mercury  is  placed,  and  to  the  greatness 
of  the  electric  action.  This  electric  action  may  result  from  a 
difference  of  potential  in  the  electric  condition  of  the  two  ex- 
tremities of  the  circuit,  which  communicate  with  the  electric 
source  employed,  or  with  some  electric  generator.1 

In  accordance  with  these  effects,  it  is  intelligible  that  if  two 
tubes,  T  T,  pointed  at  the  end,  and  containing  mercury,  are 
plunged  into  two  vessels,  V  V  (Fig.  34),  containing  acidulated 


hlllllilulllilllllllllilllM 

FIG.  34. 

water  and  mercury,  and  metallic  wires,  P  P,  Q  Q,  are  used,  first 
to  connect  the  columns  of  mercury  in  the  tubes,  and  secondly 
the  layers  of  mercury  at  the  bottom  of  the  two  vessels,  the 
tubes  being  a  little  removed  from  the  surface  of  the  mercury 
in  the  vessels,  we  shall  then  have  a  metallic  circuit,  completed 
by  two  electrolytes,  one  of  which  will  be  subjected  to  the  me- 


1  M.  M.  J.  Page  had  already  noticed  that  if  a  telephone  is  placed  in  the 
circuit  of  the  primary  helix  of  an  induction  coil,  while  the  secondary  helix 
of  this  instrument  is  placed  in  the  circuit  of  one  of  M.  Lippmann's  capil- 
lary electrometers,  a  movement  of  the  mercurial  column  of  the  electrome- 
ter takes  place  at  each  word,  and  this  movement  is  effected  toward  the 
capillary  end  of  the  tube,  in  whatever  direction  the  current  is  sent  by  the 
telephone.  This  is  because  the  mercury  always  tends  to  move  more  rapid- 
ly at  its  capillary  end  than  at  the  other  extremity. 


92  THE   TELEPHONE. 

chanical  or  electrical  effects  produced  in  the  other.  If  two  vi- 
bratory plates,  B  B,  are  placed  above  the  tubes,  and  one  of 
these  is  caused  to  vibrate,  the  other  will  reproduce  these  vibra- 
tions, influenced  by  the  vibratory  movements  communicated 
by  the  corresponding  column  of  mercury.  The  vibrations 
themselves  will  be  in  connection  with  the  electrical  discharges 
resulting  from  the  movements  of  the  column  of  mercury  in  the 
first  tube,  which  are  mechanically  produced.  If  an  electric 
generator  is  introduced  into  the  circuit,  the  effect  which  we 
have  just  analyzed  will  be  caused  by  modifications  in  the  po- 
tential of  this  generator,  in  consequence  of  electro-capillary  ef- 
fects. But  if  no  generator  is  employed,  the  action  will  result 
from  electric  currents  determined  by  the  electro-capillary  at- 
traction itself.  In  the  latter  case,  however,  the  instrument 
must  be  more  delicately  made,  in  order  to  obtain  more  sensi- 
tive electric  reaction,  and  M.  A.  Begruet  describes  his  instru- 
ment as  follows : 

"  The  instrument  consists  of  a  tube  of  thin  glass,  a  few  cen- 
timetres in  length,  containing  alternate  drops  of  mercury  and 
acidulated  water,  so  as  to  constitute  so  many  electro-capillary 
elements,  connected  in  tension.  The  two  ends  of  the  tube  are 
fused  together,  yet  so  as  to  allow  a  platinum  wire  to  touch  the 
nearest  drop  of  mercury  on  each  side.  A  small  circle  of  thin 
deal  is  fixed  at  right  angles  to  the  tube  by  its  centre,  thus  pro- 
viding a  surface  of  some  extent,  which  can  be  applied  to  the 
ear  when  the  instrument  is  a  receiver,  and  to  make  the  tube 
more  mobile  under  the  influence  of  the  voice  when  the  instru- 
ment is  a  sender.  The  following  are  the  advantages  offered 
by  instruments  of  this  construction  : 

"  1.  They  do  not  involve  the  use  of  a  battery. 

"  2.  The  disturbing  influence  of  the  resistance  of  a  long  line 
is  almost  destroyed  in  these  instruments,  although  it  is  still  ap- 
preciable in  the  Bell  telephone. 

"3.  Two  mercury  telephones,  coupled  together  as   we  de- 


FBICTION   TELEPHONES.  93 

scribed  above,  are  absolutely  correlative,  in  this  sense,  that  even 
different  positions  in  the  equilibrium  of  the  mercury  in  one  of 
them  produce  different  positions  of  equilibrium  in  the  opposite 
instrument.  It  is  therefore  possible  to  reproduce  at  a  distance, 
without  a  battery,  not  merely  faithful  indications  of  oscillatory 
movements,  which  is  done  by  the  Bell  telephone,  but  also  the 
exact  image  of  the  most  general  movements." 

Friction  Telephones. — Mr.  E.  Gray  has  quite  recently  applied 
the  principle  of  producing  sounds  by  the  friction  of  animal 
tissues  to  the  construction  of  a  speaking  telephone  which  may 
be  heard  through  a  whole  room,  like  the  singing  condenser. 
He  obtains  this  result  by  means  of  clock-work,  which  causes 
the  rotation  of  the  metallic  disk  of  which  we  have  spoken 
(p.  27),  and  on  which  a  piece  of  skin  is  so  arranged  as  to  pro- 
duce friction.  A  carbon  or  liquid  telephone  is  placed  at  the 
sending-station,  in  such  a  way  as  to  react  on  an  induction  coil, 
as  in^the  systems  of  Edison,  Navez,  or  Pollard,  and  speech  is 
reproduced  on  the  rotating  disk,  and  is  audible,  as  we  have 
said,  without  the  necessity  of  approaching  the  ear  to  the  in- 
strument. 

The  best  arrangement  of  the  metallic  disk  on  which  the  ani- 
mal tissue  rubs  is  that  of  a  cylindrical  box,  of  which  the  outer 
lid  is  made  of  a  thin  sheet  of  zinc  with  a  highly  polished, 
slightly  oxidized  surface ;  for  the  agent  of  friction,  glove- 
leather  slightly  moistened  with  acidulated  water  may  be  used, 
or  a  sinew  of  an  ox,  or  skin  taken  from  the  ear  or  tail  of 
a  pig. 

MODIFICATIONS  INTRODUCED  IN  THE  CONSTRUCTION  OF  THE 
BELL  TELEPHONES. 

The  modifications  which  we  have  been  considering  relate  to 
the  principle  of  the  instrument ;  those  which  we  have  now  to 
consider  are  only  modifications  in  the  form  and  arrangement 
of  the  different  organs  which  form  the  Bell  telephone  itself, 


94  THE    TELEPHONE. 

and  which  have  been  designed  with  the  object  of  increasing 
the  intensity  and  distinctness  of  the  sounds  produced. 

Telephones  with  Several  Diaphragms. — When  we  remember 
that  the  induced  currents  caused  in  a  magnet  result  from  the 
vibratory  movements  of  the  diaphragm,  and  that  these  are  pro- 
duced by  the  vibrations  of  the  stratum  of  air  interposed  be- 
tween this  diaphragm  and  the  vocal  organ,  it  necessarily  fol- 
lows that  if  these  vibrations  of  the  air  react  on  several  dia- 
phragms, each  attached  to  its  electro-magnetic  organ,  several 
induced  currents  might  be  caused  simultaneously,  and  if  these 
were  properly  connected,  their  effects  on  the  receiver  would  be 
so  much  the  more  intense,  since  the  sounds  produced  would  re- 
sult from  the  combination  of  several  sources  of  sound.  Sev- 
eral inventors,  starting  from  this  argument,  have  planned  in- 
struments of  varying  ingenuity,  which  we  will  now  describe, 
but  without  being  able  to  declare  who  was  the  first  to  realize 
this  idea.  It  is,  in  fact,  so  simple  that  it  probably  suggested 
itself  to  the  minds  of  several  inventors  at  the  same  time ;  and 
we  see  that  while  M.  Trouve  proposed  this  improvement  in 
France  in  November,  1877,  it  was  tried  in  America  and  dis- 
cussed in  England,  where  indeed  it  was  not  expected  to  pro- 
duce very  favorable  results.  Mr.  Preece  wrote  on  the  subject 
in  a  paper  entitled  "On  some  Physical  Points  connected  with 
the  Telephone,"  which  was  published  in  April,  1878.  He  ob- 
serves that  all  the  attempts  to  improve  the  telephone  have  end- 
ed in  disappointment  and  failure.  One  of  the  first  attempts 
of  the  kind  was  made  by  Mr.  Wilmot,  who  expected  to  obtain 
favorable  results  by  augmenting  the  number  of  diaphragms, 
helices,  and  magnets,  connecting  the  helices  in  a  series,  and 
causing  them  to  act  simultaneously,  so  as  to  increase  the  ener- 
gy of  the  currents  developed  by  the  influence  of  the  voice; 
but  experience  showed  that  when  the  instrument  acted  direct- 
ly, the  vibratory  effect  of  each  of  the  diaphragms  decreased  in 
proportion  to  their  number,  and  the  general  effect  remained 


95 

the  same  as  with  a  single  diaphragm.  Mr.  Wilmot's  instru- 
ment was  made  in  the  beginning  of  October,  1877,  and  that  of 
M.  Trouve  was  only  an  imitation  of  it. 

On  the  other  hand,  we  see  that  if  the  telephones  with  several 
membranes  were  not  successful  in  England,  this  was  not  the 
case  in  America,  for  the  telephones  which  experience  has  shown 
to  give  the  best  results  in  that  country  are  those  of  Mr.  Elisha 
Gray  and  Mr.  Phelps,  and  these  have  several  diaphragms.  It 
is  evident  that  there  are  details  of  construction  in  these  instru- 
ments which  may  appear  insignificant  in  theory,  and  which  are 
notwithstanding  very  important  from  a  practical  point  of  view, 
and  we  believe  that  it  is  to  this  circumstance  that  instruments 
of  this  kind  owe  their  success  or  failure.  Thus,  for  example, 
it  seems  that  the  vibrations  of  air  caused  in  the  mouth-piece 
ought  to  be  immediately  directed  on  the  surface  of  the  dia- 
phragms by  means  of  distinct  channels;  it  is  necessary  that 
the  empty  space  round  each  diaphragm  should  be  sufficiently 
limited  to  prevent  echoes  and  interruptions,  unless  the  case  is 
so  large  that  there  is  no  danger  of  such  effects.  Above  all,  it 
is  necessary  that  the  organs  should  be  fixed  in  some  material 
unsusceptible  of  reverberation,  and  for  this  reason  a  preference 
is  given  to  iron  or  ebonite.  It  is  certain  that,  when  the  instru- 
ment is  properly  made,  its  effects  are  superior  to  those  of  the 
Bell  telephones ;  and  it  is  asserted  in  the  Telegraphic  Journal 
that  experiments  were  made  with  one  of  these  instruments  be- 
fore the  Royal  Society,  in  London,  May  1st,  1878,  and  that  the 
intensity  of  sound  was  in  proportion  to  the  number  of  dia- 
phragms. This  instrument  was  designed  by  Mr.  Cox  Walker, 
of  York,  and  possessed  eight  diaphragms.  He  considers  that 
this  is  the  arrangement  which  gives  the  best  results. 

Mr.  Elisha  Gray's  System. — Mr.  Elisha  Gray's  last  system, 
which  we  represent  in  Fig.  35,  is  one  of  those  which  have  given 
the  best  effects.  It  is  made,  as  we  see,  of  two  telephones,  side 
by  side,  to  which  correspond  two  tubes,  issuing  from  a  common 


THE    TELEPHONE. 


mouth-piece,  E.     One  of  these  telephones  is  seen  in  section  in 
the  plate,  the  other  in  elevation,  and  they  correspond  to  the 


FIG.  35. 


two  branches  of  a  nickel  -  plated  horseshoe  magnet,  N  IT  S, 
which  may  serve  as  a  suspension  ring.  In  that  part  of  the 
plate  which  represents  the  section,  the  induction  coil  is  shown 
in  B,  and  the  magnetic  core,  of  soft  iron,  in  A,  which  is  screwed 
to  the  polar  end  of  the  magnet  S ;  the  vibrating  plate  is  in  L  L, 
and,  as  we  see,  the  tube  of  the  mouth-piece  terminates  on  its 
surface. 

In  another  model  there  are  four  telephones  side  by  side,  in- 
stead of  two,  and  the  effects  produced  are  still  more  marked. 

Mr.  Phelps's  System. — This  system  is  only  deduced  from  the 
last,  but  there  are  two  models  of  it.  In  the  larger  one,  which 


97 

makes  it  possible  to  hear  as  distinctly  as  if  the  person  with 
whom  conversation  is  held  were  speaking  in  a  loud  voice  in  the 
same  room,  the  two  telephones  are  placed  parallel  to  each  other, 
and  so  as  to  present  their  diaphragms  vertically ;  the  space  be- 
tween these  two  diaphragms  is  occupied  by  a  vertical  tube,  ter- 
minating at  its  lower  end  in  a  horizontal  tube  corresponding  to 
the  centres  of  the  two  diaphragms,  and  on  this  tube  the  mouth- 
piece is  fitted,  which  projects  outside  the  box  in  which  the  in- 
strument is  enclosed.  The  induction  coils,  and  the  magnetic 
cores  which  traverse  them,  follow  the  axis  of  the  system,  and 
seem  to  constitute  the  axis  of  a  wheel  which  is  polarized  by 
the  poles  of  a  horseshoe  magnet,  of  which  the  position  with 
reference  to  the  surface  of  the  diaphragms  can  be  regulated  by 
movable  screws.  The  appearance  of  the  instrument  somewhat 
resembles  a  gyroscope,  resting  by  a  horizontal  axis  on  two 
shafts  which  issue  from  a  flattened  horseshoe  magnet. 

Above  this  system  there  is  the  electro-magnetic  apparatus  of 
the  call-bell,  in  which  there  is  nothing  peculiar,  and  which  is 
like  the  German  alarums,  of  which  we  shall  speak  at  the  end 
of  this  account.  This  instrument  is  remarkable  for  strength 
and  clearness  of  sound,  and  especially  for  its  freedom  from  the 
Punch  and  Judy  voice  so  displeasing  in  other  telephones. 

Mr.  Phelps's  small  model  is  in  the  form  of  an  oblong  or  el- 
liptical snuffbox,  of  which  the  two  centres  are  occupied  by  two 
telephonic  systems,  influenced  by  the  same  magnet.  This  mag- 
net is  placed  in  a  horizontal  position  below  the  snuffbox,  and 
its  poles  correspond  to  the  magnetic  cores  of  the  coils.  These 
cores  are  made  of  iron  tubes,  split  longitudinally  in  order  to 
destroy  irregular  induction  reactions,  and  the  iron  diaphragms 
rest  on  five  spiral  springs,  which  raise  them  above  the  mag- 
netic system.  On  their  other  surface  the  diaphragms  are 
provided  with  rings  of  some  semi -elastic  substance,  which 
prevent  the  central  vibrations  of  the  disks  from  becoming  com- 
plicated by  those  of  their  edges.  The  lid,  hollowed  out  in  very 

5 


98  THE    TELEPHONE. 

shallow  cavities,  is  next  placed  upon  the  disks,  and  there  are 
channels  of  communication  in  it  to  serve  as  a  sounding-box. 
The  mouth-piece  corresponds  to  one  of  these  cavities,  and  the 
other  is  closed  by  a  small  metallic  stopper,  which  can  be  with- 
drawn to  regulate  the  instrument  when  necessary.  Since  the 
vibrations  of  air  are  transmitted  by  the  channels  to  both  cavi- 
ties, the  two  telephones  act  together,  although  at  first  sight 
only  one  of  them  seems  to  be  required  to  produce  the  effect. 

Mr.  Phelps  praises  the  simultaneous  effects  produced  on  the 
two  instruments,  which  he  ascribes,  first,  to  the  semi-elastic  ring 
surrounding  the  rim  of  each  disk,  and  acting  as  the  hammer  of 
the  ear, that  is,  as  a  damper;  then,  to  the  longitudinal  splits  of 
the  magnetic  core,  and  lastly  to  the  small  size  of  the  cavities 
left  above  the  vibrating  disks.  The  instrument  is  made  of 
ebonite,  grooved  on  the  surface  in  order  to  give  a  better  grasp 
to  the  hand. 

Mr.  Phelps  has  a  new  model,  called  the  crown  telephone,  which 
is  now  in  use  in  America,  together  with  Mr.  Edison's  carbon 
sender.  In  it  each  of  the  two  systems  of  the  large  model  we 
have  described  is  worked  by  six  horseshoe  magnets  radiating 
round  the  magnetic  core,  and  so  arranged  &at  the  north  poles 
correspond  to  this  core,  and  the  other  poles  to  the  circular  rim 
of  the  diaphragm.  In  this  way  the  magnetic  field  is  consider- 
ably enlarged,  and  the  sound  much  intensified. 

In  experiments  recently  made  at  Dr.  Wells' s  church,  New 
York,  an  assembly  of  three  hundred  people  were  able  to  hear 
speech  and  vocal  or  instrumental  music  distinctly  in  different 
parts  of  the  hall. 

Mr.  Cox  Walker's  System. — This  system,  on  which  we  have 
already  said  a  few  words,  has  exactly  the  arrangement  of  that 
by  Mr.  Elisha  Gray.  The  magnets  which  act  upon  the  dia- 
phragms are  horseshoe,  and  separate  pipes,  issuing  from  a 
common  mouth-piece,  direct  the  vibrations  of  air  on  the  dia- 
phragms. These,  indeed,  are  only  defined  parts  of  one  dia- 


TBOUVE'S  SYSTEM.  99 

phragm,  bounded  in  a  circle  by  mouth-pieces  corresponding  to 
the  air-pipes,  and  sufficiently  restricted  on  their  edges  to  limit 
the  field  of  vibration. 

3/.  Trouvffs  System. — M.  Trouve  has  simplified  the  arrange- 
ment of  telephones  with  a  double  diaphragm,  by  designing  the 
instrument  so  as  to  make  Bell's  bar  magnet  react  by  both 
poles  at  once  on  several  disks.  For  this  purpose  he  employs 
a  tubular  magnet,  and  winds  a  helix  throughout  its  whole 
length,  as  we  see  in  Fig.  36.  This  magnet  is  maintained  in  a 


FIG.  36. 

fixed  position  in  the  centre  of  a  small  cylindrical  box,  of  which 
the  base  is  slightly  funnel-shaped,  thus  acting  as  a  mouth-piece 
and  acoustic  tube.  It  is  consequently  pierced  in  the  centre 
with  a  hole  larger  at  a,  the  station  for  speaking,  than  on  the 
opposite  side,  b.  Between  the  base  and  the  poles  of  the  mag- 
net there  are  two  vibrating  iron  plates,  M,  M',  one  of  which,  M, 
is  pierced  with  a  hole,  a,  of  the  same  diameter  as  the  hollow 
part  of  the  magnet,  and  consequently  smaller  than  that  of  the 
mouth-piece.  Finally,  several  other  plates,  ny  n,  n,  are  ranged 
in  parallel  lines  between  these  two  plates,  so  that  the  magnet 
and  its  helix  may  pass  through  them. 

When  anything  is  said  before  the  mouth-piece  cr,  the  waves 
of  sound  encountering  the  edges  of  the  plate  M  place  it  in  vi- 


100  THE    TELEPHONE. 

bration,  and,  continuing  their  passage  inside  the  tubular  mag- 
net, they  cause  the  plate  M'  to  vibrate  at  the  same  time  as  M. 
A  double  inducing  action,  therefore,  takes  place  on  the  tubular 
magnet,  and  this  is  translated  by  the  induced  currents  devel- 
oped in  the  helix,  which  have  greater  energy,  since  each  of  the 
plates  intensifies  the  magnetic  effects  produced  at  the  pole  op- 
posite to  the  one  they  influence,  which  is  always  the  case  with 
bar  magnets  when  the  inactive  pole  is  provided  with  an  arma- 
ture. This  advantage  may  even  be  obtained  in  the  case  of 
ordinary  telephones,  if  the  screw  which  holds  the  magnet  is 
placed  in  contact  with  a  mass  of  soft  iron. 

In  M.  Trouve's  arrangement  the  induced  currents,  therefore, 
possess  greater  energy;  but  he  adds  that  the  sounds  repro- 
duced will  also  be  strengthened  by  the  multiplicity  of  vibra- 
tory effects,  and  by  the  enlargement  of  the  magnetic  effects, 
which  results  from  a  better  arrangement  of  the  magnets. 

"  When  the  ear  is  placed  at  a,"  M.  Trouve  writes,  "  it  per- 
ceives immediately  the  sounds  produced  by  the  first  plate,  M, 
and  those  of  the  second  plate  reach  the  ear  through  the  inte- 
rior of  the  magnet.  This  new  arrangement  is  well  adapted  for 
an  experimental  comparison  of  the  results  produced  by  a  tele- 
phone with  a  single  membrane  (a  Bell  telephone),  and  those 
produced  by  a  telephone  with  several  membranes.  It  is,  in 
fact,  enough  to  listen  at  the  two  faces  of  the  telephone  alter- 
nately, in  order  to  perceive  at  once  the  difference  of  intensity 
in  the  sounds  produced.  Those  collected  at  a,  on  the  side  of 
the  pierced  iron  plate,  appear  manifestly  doubled  in  intensity 
compared  with  those  collected  at  b  on  the  side  of  the  simple 
membrane  which  forms  the  ordinary  telephone. 

"  The  difference  is  still  more  striking  if,  in  transmitting  or 
receiving  a  sound  of  invariable  intensity  through  a  multiple 
telephone,  the  unbroken  membrane  M'  is  repeatedly  prevented 
from  vibrating." 

Before  making  this  arrangement  M.  Trouve  had  planned  an- 


DEMOGET'S  SYSTEM.  101 

other,  which  he  presented  to  the  Academic  des  Sciences,  No- 
vember 26th,  1877,  and  which  we  have  glanced  at  in  the  be- 
ginning of  this  chapter.  He  describes  it  in  these  terms : 

"  In  order  to  increase  the  intensity  of  the  effects  produced 
in  the  Bell  telephone,  I  have  substituted  for  the  single  mem- 
brane a  cubic  chamber,  of  which  each  face  is,  with  one  excep- 
tion, formed  of  a  vibrating  membrane.  Each  of  these  mem- 
branes, put  in  vibration  by  the  same  sound,  influences  a  fixed 
magnet,  which  is  also  provided  with  an  electric  circuit.  In 
this  way,  by  connecting  all  the  currents  generated  by  the  mag- 
nets, a  single  intensity  is  obtained,  which  increases  in  propor- 
tion to  the  number  of  magnets  influenced.  The  cube  might 
be  replaced  by  a  polyhedron,  of  which  the  faces  might  be 
formed  of  an  indefinite  number  of  vibrating  membranes,  so 
as  to  obtain  the  desired  intensity. 

M.  DemoyeCs  System. — Several  other  systems  of  telephones 
with  multiple  membranes  have  been  proposed.  One  of  them, 
planned  by  M.  Demoget,  consists  in  placing  before  the  vibra- 
ting disk  of  the  ordinary  Bell  telephone,  separated  by  the 
space  of  a  millimetre,  one  or  two  similar  vibrating  disks,  tak- 
ing care  to  pierce  in  the  centre  of  the  first  a  circular  hole  of 
the  same  diameter  as  that  of  the  bar  magnet,  and  to  pierce  a 
larger  hole  in  the  second  membrane.  The  inventor  asserts 
that  the  distinctness  as  well  as  the  intensity  of  sounds  is  in- 
creased in  this  way. 

"By  this  arrangement,"  says  M.  Demoget,  "since  the  vibra- 
ting magnetic  mass  is  larger  in  proportion  to  the  magnet,  the 
electro-motive  force  of  the  currents  generated  is  increased,  and 
consequently  the  vibrations  of  the  disks  of  the  second  telephone 
are  more  perceptible." 

Mr.  M' Tiff  he's  Telephone. — In  this  telephone,  which  has  sev- 
eral diaphragms,  there  is  a  horseshoe  magnet,  and  instead  of 
placing  the  coils  upon  the  poles,  there  is  a  single  coil  fastened 
to  an  iron  core,  which  is  inserted  between  wide  polar  appen- 


102 


THE    TELEPHONE. 


dices  fitted  to  the  two  poles  of  the  magnet.     These  appendices 
consist  of  thin  plates,  which  act  as  vibrating  plates. 

Modifications  in  the  Arrangement  of  Telephonic  Organs. — 
We  see  that  the  forms  given  to  the  Bell  telephone  are  very  va- 
ried, and  this  is  still  more  the  case  with  its  constituent  organs, 
without,  however,  producing  any  remarkable  improvements. 
Mr.  Preece  observes  that  little  has  been  gained  by  varying  the 
size  and  strength  of  the  magnets,  and  the  best  effects  have  been 


Fia.  37. 


obtained  by  using  the  horseshoe  magnets  directed  by  Mr.  Bell 
himself.  The  telephone  was  certainly  introduced  into  Europe 
with  the  arrangement  which  is  theoretically  the  best,  although 
Mr.  Bell  is  still  occupied  in  improving  it.  This  is  also  tlio 
opinion  of  M.  Hellesen,  who,  like  Mr.  Preece,  has  made  many 
experiments  on  this  point;  but  this  has  not  deterred  several 
people  from  declaring  that  they  have  discovered  the  way  of 
making  a  telephone  speak  so  as  to  be  audible  to  an  assembly 
of  people. 


EIGHI  TELEPHONE. 


103 


Of  the  different  instruments  made  with  this  object,  that  of 
M.  Righi  seems  to  be  the  most  important.  It  was  lately  tried 
with  success  at  the  Academic  dcs  Sciences,  the  Conservatoire 
des  Arts  et  Metiers,  and  the  Press  pavilion  of  the  Exhibition. 

The  receiver  is  only  a  Bell  telephone  of  large  size,  with  a 
diaphragm  of  parchment,  L  L  (Fig.  37),  in  the  centre  of  which 
there  is  a  sheet-iron  disk,  F.  This  membrane  is  stretched  on 
a  large  funnel,  E,  which  is  fixed  on  a  box,  C  C,  containing  the 
electro -magnetic  coil  B;  and  the  magnet  N  S,  much  larger 
than  in  the  ordinary  instruments,  issues  from  the  box,  and 
serves  as  its  support. 

The  sender  resembles  the  one  represented  in  Fig.  19,  except 
that,  instead  of  liquid,  M.  Righi  employs  plumbago  mixed  with 
powdered  silver,  and  the  platinum  needle  is  replaced  by  a  me- 
tallic disk,  D  (Fig.  38).  The  receiver  I,  which  contains  the 
powder,  is  supported  on  a  spring,  R,  which  can  be  pushed  up 
and  down  by  a  regulating  screw,  V,  and  the  whole  is  fitted  into 
a  box,  C  C,  and  supported  on  a  foot,  P.  The  speaker  places 


Fio.  SS. 


himself  above  the  mouth-piece  E,  and  the  vibrations  transmit- 
ted to  the  membrane  L  L  cause  the  variations  of  resistance  in 
I  which  are  necessary  for  the  transmission  of  speech,  as  in  the 
Edison  svstem.  Two  Bunsen  cells  are  enough  to  set  the  in- 


104  THE    TELEPHONE. 

strument  at  work,  and  it  will  make  the  sound  of  a  trumpet  or 
flute  audible  throughout  a  room.  Vocal  music,  which  is  less 
intense,  is  necessarily  transmitted  to  a  rather  less  distance,  and 
words  spoken  in  the  natural  voice  are  heard  by  those  standing 
about  two  yards  and  a  half  from  the  instrument. 

The  maximum  distance  at  which  the  instrument  has  been 
worked  with  the  battery  only  is  twenty-eight  miles,  the  dis- 
tance between  Bologna  and  Ferrara ;  and  for  greater  distances 
it  is  necessary  to  have  recourse  to  induction  coils. 

In  this  case  an  induction  coil  is  introduced  into  the  circuit 
at  each  station,  and  its  primary  wire  is  traversed  by  a  current 
from  the  local  battery,  and  so  also  is  the  sender,  which  is  else- 
where connected  with  the  receiver  by  a  commutator.  The  sec- 
ondary circuit  of  these  coils  is  completed  through  the  earth  and 
line  wire.  From  this  arrangement  it  follows  that  the  induced 
current  which  influences  the  receiver  in  correspondence  only 
produces  its  effect  after  a  second  induction,  produced  on  the 
primary  wire  of  the  local  coil,  and  it  appears  that  this  is  a  suffi- 
cient effect ;  but  the  advantage  of  this  arrangement  is,  that  it 
is  possible  to  receive  and  transmit  sounds  without  the  aid  of 
anything  but  the  commutator. 

Among  other  arrangements  which  have  been  suggested,  we 
may  mention  one  in  which,  instead  of  the  bar  magnet,  a  horse- 
shoe magnet  is  used,  with  a  vibrating  plate  placed  between  its 
poles.  For  this  purpose  the  poles  are  tipped  with  iron,  and 
one  of  them  is  pierced  with  a  hole  which  corresponds  to  the 
mouth-piece  of  the  instrument.  The  two  branches  of  the  mag- 
net are  also  furnished  with  magnetizing  helices.  When  any- 
thing is  spoken  before  the  hole,  the  vibrating  plate  causes  in- 
duced currents  in  the  two  helices :  these  currents  would  be  of 
opposite  direction  if  the  poles  were  of  like  nature,  but,  since 
the  magnetic  poles  are  of  contrary  nature,  they  are  in  the  same 
direction.  The  vibrating  plate  then  acts  like  the  two  plates  of 
M.  Trouve's  instrument,  which  we  have  described  above. 


ARRANGEMENT.  105 

In  another  arrangement,  lately  made  by  Ader,  the  receiver  is 
only  an  ordinary  two-branched  magnet,  of  which  the  armature 
is  supported,  at  about  two  millimetres  from  its  poles,  by  a  glass 
plate  to  which  it  is  glued,  and  the  plate  itself  is  fastened  to 
two  rigid  supports.  In  order  to  hear,  it  is  only  necessary  to 
apply  the  ear  to  the  plate.  The  sender  is  a  movable  rod  of 
iron  or  carbon,  which  rests  on  a  fixed  piece  of  carbon,  with  no 
pressure  except  its  own  weight,  and  it  supports  a  concave  disk, 
to  which  the  speaker  applies  his  mouth.  These  two  parts  are 
so  arranged  as  to  move  horizontally,  so  that,  when  the  instru- 
ment is  suspended,  the  circuit  is  forcibly  disconnected  by  the 
fact  of  its  position,  and  is  therefore  closed  until  any  one  takes 
it  up  to  speak.  Speech  is  well  reproduced  by  this  system,  and 
may  be  transmitted  to  some  distance  if  it  is  made  on  a  larger 
scale. 

Again,  an  anonymous  inventor,  in  a  little  note  inserted  in 
Les  Mondes,  February  7th,  1878,  writes  as  follows:  "Since  the 
intensity  of  the  currents  produced  in  the  telephone  is  in  pro- 
portion to  the  mass  of  soft  iron  which  vibrates  before  the  pole 
of  the  magnet,  and  since,  on  the  other  hand,  the  plate  is  sensi- 
tive in  proportion  to  its  tenuity,  I  employ,  instead  of  the  or- 
dinary plate,  one  reduced  by  nitric  acid  to  the  least  possible 
thickness,  and  I  fix  it  to  a  circle  of  soft  iron,  which  keeps  it 
stretched  and  forms  part  of  the  same  substance.  This  circle 
is  placed  in  a  circular  opening  made  inside  the  compartment. 
The  intensity  of  a  telephone  is  much  increased  when  such  a 
system  replaces  the  ordinary  plate,  even  at  one  end  of  the  line." 

In  order  to  obtain  vibrating  plates  of  extreme  tenuity,  M.  E. 
Duchemin  thought  of  employing  very  thin  plates  of  mica, 
sprinkled  with  pulverized  iron  fixed  to  the  plate  by  a  layer  of 
silicate  of  potash.  The  inventor  asserts  that  it  is  possible  to 
correspond  in  a  low  voice  with  the  aid  of  this  system ;  but  it 
has  this  inconvenience,  that  the  plate  will  be  broken  by  speak- 
ing too  loud. 

5* 


106  THE    TELEPHONE. 

Professor  Jorgenson,  of  Copenhagen,  has  also  made  a  Bell 
telephone  which  produces  very  intense  sounds,  and  which  has 
permitted  him  to  observe  some  curious  effects.  In  this  instru- 
ment the  magnet  is  made  in  a  mode  analogous  to  Nickles's 
tubular  magnets.  There  is,  first,  a  cylindrical  magnet  with  a 
core  of  soft  iron  at  its  upper  end,  to  which  the  coil  is  fitted ; 
next,  a  magnetized  tube,  formed  of  a  steel  ring,  which  encloses 
the  first  magnetic  system,  and  is  connected  with  it  by  an  iron 
tube.  Finally,  above  the  polar  extremities  of  this  system,  there 
is  the  vibrating  disk,  with  the  same  arrangement  as  that  of  or- 
dinary telephones,  and  of  which  the  superficies  is  large.  If 
this  plate  is  only  a  millimetre  in  thickness,  the  words  spoken 
can  be  heard  throughout  a  room ;  but  the  sounds  lose  their 
clearness  when  the  ear  is  approached  to  the  vibrating  plate,  the 
words  are  confused,  and  there  is  the  reverberation  which  is  ob- 
served on  speaking  in  a  place  apt  to  produce  echoes:  the  lis- 
tener is,  in  fact,  stunned  by  the  sounds  produced.  On  using  a 
thicker  plate — one,  for  example,  of  three  or  four  millimetres — 
the  telephone  only  produces  the  effect  of  the  ordinary  instru- 
ments, and  it  is  necessary  to  apply  the  ear  to  it. 

M.  Marin  Maillet,  of  Lyons,  has  suggested  that  the  sounds 
reproduced  by  the  telephone  might  be  increased  by  reflecting 
them  through  a  certain  number  of  reflectors,  which,  by  concen- 
trating them  in  a  focus  on  a  resonator,  would  considerably  en- 
large them.  Since  this  idea  was  not  accompanied  by  experi- 
ments, it  can  hardly  be  regarded  as  serious. 

TELEPHONIC  EXPERIMENTS. 

Since  Mr.  Bell's  experiments,  of  which  an  account  has  been 
given  in  the  early  part  of  this  work,  much  study  has  been 
given  by  men  of  science  and  inventors  to  the  effects  produced 
in  this  curious  instrument,  so  as  to  ascertain  its  theory  and  de- 
duce improvements  in  its  construction.  We  will  take  a  glance 
at  these  researches  in  succession. 


• 


••I/. 


TELEPHONIC    EXPERIMENTS.          */rV,        10^ 

°// 


Experiments  on  the  Effects  produced  by  Voltaic  and  Indul 
Currents. — The  comparative  study  of  the  effects  produced  in 
the  telephone  by  voltaic  and  induced  currents  was  one  of  the 
first  and  most  important.  In  1873,  as  we  have  seen,  Mr.  Eli- 
sha  Gray  converted  the  voltaic  currents,  which  he  employed  to 
cause  the  vibrations  of  his  transmitting  plate,  into  induced  cur- 
rents by  means  of  an  induction  coil,  such  as  Ruhmkorff's.  The 
voltaic  currents  then  traversed  the  primary  helix  of  the  coil, 
and  the  induced  currents  reacted  on  the  receiving  instrument, 
producing  on  its  electro-magnetic  system  the  vibrations  excited 
at  the  sending -station.  When  Mr.  Edison  designed  his  bat- 
tery telephone,  he  had  recourse  to  the  same  means  to  work  his 
receiving  telephone,  since  he  had, ascertained  that  induced  cur- 
rents were  superior  to  voltaic  currents.  But  this  peculiarity 
of  Mr.  Edison's  arrangement  was  not  clearly  understood  from 
the  descriptions  which  reached  Europe,  so  that  several  persons 
believed  that  they  had  invented  this  arrangement — among  oth- 
ers, Colonel  Navez  and  MM.  Pollard  and  Gamier. 

Colonel  Navez,  in  an  interesting  paper  on  the  new  telephon- 
ic system,  presented  to  the  Belgian  Royal  Academy  February 
2d,  1878,  only  suggests  this  arrangement  as  a  mode  of  repro- 
ducing speech  at  a  great  distance;  but  he  quotes  no  experi- 
ment which  distinctly  shows  the  advantages  of  this  combina- 
tion. Twenty  days  later,  MM.  Pollard  and  Gamier,  unac- 
quainted with  Colonel  Navez's  researches,  sent  to  me  the  re- 
sults they  had  obtained  by  similar  means,  and  these  results 
appeared  to  me  so  interesting  that  I  communicated  them  to  the 
Academic  des  Sciences,  February  25th,  1878.  In  order  that 
the  importance  of  these  results  may  be  clearly  understood,  I 
will  repeat  the  text  of  M.  Pollard's  letter,  addressed  to  me  on 
February  20th,  1878 : 

"  With  the  object  of  increasing  the  variations  of  electric  in- 
tensity in  the  Edison  system,  we  induce  a  current  in  the  cir- 
cuit of  a  small  Ruhmkorff  coil,  and  we  fix  the  receiving  tele- 


108  THE   TELEPHONE. 

phone  to  the  extremities  of  the  induced  wire.  The  current 
received  has  the  same  intensity  as  that  of  the  inducing  current, 
and  consequently  the  variations  produced  in  the  current  which 
works  the  telephone  have  a  much  wider  range.  The  intensity 
of  the  transmitted  sounds  is  strongly  increased,  and  the  value 
of  this  increase  depends  upon  the  relative  number  of  spirals  in 
the  inducing  and  induced  circuits.  Our  attempts  to  determine 
the  best  proportions  have  been  laborious,  since  it  is  necessary 
to  make  a  coil  for  each  experiment ;  we  have  hitherto  obtain- 
ed excellent  results  with  a  small  Ruhmkorff  coil  reduced  to  its 
simplest  form,  that  is,  without  condenser  or  contact-breaker. 
The  inducing  wire  is  No.  16,  and  is  wound  in  five  layers;  the 
induced  wire  is  Xo.  32,  and  in  twenty  layers.  The  length  of 
the  coil  is  seven  centimetres, 

"The  following  is  the  most  remarkable  and  instructive  ex- 
periment: When  setting  the  sender  to  work  with  a  single 
Daniell  cell,  there  is  no  appreciable  effect  at  the  receiving-sta- 
tion, at  least  in  the  telephone  which  I  have  made,  when  it  is 
in  immediate  connection  with  the  circuit ;  after  inserting  the 
small  induction  coil,  sounds  become  distinctly  audible,  and 
their  intensity  equals  that  of  good  ordinary  telephones.  Since 
the  battery  current  is  only  moderately  intense,  the  points  of 
plumbago  are  not  worn  down,  and  the  regulating  apparatus 
lasts  for  a  long  while,  AVhen  a  stronger  battery  is  used,  con- 
sisting of  six  cells  of  bichromate  of  potash  (in  tension)  or 
twelve  Leclanche  cells,  sufficient  intensity  is  obtained  by  the 
direct  action  to  make  sounds  nearly  as  audible  as  in  ordinary 
telephones ;  but  when  the  induction  coil  is  inserted,  the  sounds 
become  much  more  intense,  and  may  be  heard  at  a  distance  of 
from  fifty  to  sixty  centimetres  from  the  mouth-piece.  Songs 
may,  under  such  circumstances,  be  heard  at  a  distance  of  sev- 
eral yards ;  but  the  relative  increase  does  not  appear  to  be  so 
great  as  in  the  case  of  the  single  Daniell  cell" 

On  the  other  hand,  Les  Mondes^  March  7th,  1878,  contains 


LurrsrTs  EXPEEIMESTTS.  109 

-.:'  •-.  =-••  ••'.•:•'. 

?::;--:     :  J  ;.;.--.-.-   •  • 
proved  that  the  introdoction  of 
csrit  which  connect*  the  two 
tensity  of  sonnd.    Tbe  maxsanm  effect »  produced  fey  placing 
one  dose  to  the  tiansmitfiug,  and  the  ether  dose  to  the  remr- 

use.    The  inducing  wire  of  a  Ruhmkorff  coO,  when  introdnced 
into  such  a  circuit,  excited  no  sensible  effects  of  ind action  in 

phone  in  connection  with  this  enemt  at  wott.    Bnt  the  ear- 

vou>  ot  a  v-jJuJke  macnme  pvmtnees  soands  icsenuunf  the  IIPJBH 
of  a  dram,  which  are  deafening  when  the  ear  is  appfied  to  the 

of  a  metre.  Ilie  carrents  of  a  Bahadborff  nnehne  are  ftm 
more  c  ncigetic,  and  the  sonnd  fib  a  whole  room.  I>T 
:;•-_-  :-.:  ?-<:  -.  :  :\;  ..-:  :  :-;  -  ;..  :  ., 
thron^i  different  tones,  winch  are  always  in  unison  with  the 
breaks  of  the  emreut,  at  feast  up  to  a  certain  pitch. 

::..•:••      :  :   .       '.irj  :•     :       '    -.  -       -   v.    :•  -1-  ,:   ;-.   -"     :     - 
the  telephone  he  proposes  to  regulate  in  the  ciren^  of  an  in- 


-   -   ::,:- 


110  THE    TELEPHONE. 

phones  in  correspondence  are  intense  in  proportion  to  the  de- 
gree of  unison  in  the  vibrations  produced  by  them,  it  is  neces- 
sary to  select  those  which  emit  the  same  sounds  for  the  same 
given  note ;  and  the  mode  we  have  just  described  may  be  em- 
ployed with  advantage,  since  it  will  be  enough  to  observe  what 
instruments  give  the  same  note  in  the  condition  of  maximum 
sensibility,  when  regulated  in  the  same  way  by  the  induction 
machine. 

It  is  very  important  that  the  telephones  in  correspondence 
should  be  well  matched,  not  only  to  insure  clear  transmissions, 
but  also  with  reference  to  the  tone  of  voice  of  those  who  are 
to  use  it.  The  sound  becomes  more  audible  when  the  tone  of 
voice  corresponds  to  the  telephonic  tone ;  and  for  this  reason 
some  telephones  repeat  the  voices  of  women  and  children  bet- 
ter than  those  of  men,  and  with  others  the  reverse  takes  place. 

The  telephonic  vibrations  vary  in  different  instruments,  and 
these  variations  may  be  noted  in  the  way  we  have  indicated. 

The  advantages  of  induced  currents  in  telephonic  transmis- 
sions may  be  easily  understood,  if  we  consider  that  the  varia- 
tions of  resistance  in  the  circuit,  resulting  from  the  greater  or 
less  range  in  the  vibrations  of  the  transmitting  plate,  are  of 
constant  value,  and  can  only  manifest  their  effects  distinctly  in 
short  circuits ;  consequently  the  articulate  sounds  which  result 
from  them  can  only  be  really  appreciable  in  circuits  of  great 
resistance.  According  to  Mr.  Warren  de  la  Rue's  experiments 
(reported  in  the  Telegraphic  Journal,  March  1st,  1878),  tho 
currents  produced  by  the  vibrations  of  the  voice  in  an  ordinary 
telephone  represent  in  intensity  those  of  a  Daniell  cell  travers- 
ing 100  megohms  of  resistance  (or  10,000,000  kilometres) ; 
and  it  is  plain  that  the  simple  question  of  greater  or  less  inten- 
sity in  the  currents  acting  on  the  receiving  telephone  is  not 
the  only  thing  we  have  to  consider.  "With  an  energetic  bat- 
tery, it  is  evident,  in  fact,  that  the  differential  currents  will  al- 
ways be  more  intense  than  the  induced  currents  produced  by 


INDUCED    CURRENTS.  Ill 

the  action  of  the  instrument  I  myself  am  inclined  to  believe 
that  induced  currents  owe  the  advantages  they  possess  to  the 
succession  of  inverse  currents  and  their  brief  duration.  These 
currents,  of  which  M.  Blaserna  considers  that  the  duration  does 
not  exceed  -^  of  a  second,  are  much  more  susceptible  than 
voltaic  currents  of  the  multiplied  vibrations  which  are  charac- 
teristic of  phonetic  vibrations,  and  especially  since  the  succes- 
sion of  inverse  currents  which,  take  place  discharge  the  line, 
reverse  the  magnetic  effects,  and  contribute  to  make  the  action 
more  distinct  and  rapid.  We  cannot,  therefore,  be  surprised 
that  the  induced  currents  of  the  induction  coil,  which  can  be 
produced  under  excellent  conditions  at  the  sending -station, 
since  the  circuit  of  the  voltaic  current  is  then  very  short,  are 
able  to  furnish  results,  not  only  more  effective  than  the  voltaic 
currents  from  which  they  take  their  origin,  but  even  than  the 
induced  currents  resulting  from  the  action  of  the  Bell  tele- 
phone, since  they  are  infinitely  more  energetic. 

As  for  the  effects  produced  by  the  currents  of  Bell  tele- 
phones, which  are  relatively  great  when  we  consider  their  size, 
they  are  easily  explained  from  the  fact  that  they  are  produced 
under  the  influence  of  the  vibrations  of  the  telephone  plate, 
so  that  their  variations  of  intensity  always  maintain  the  same 
proportion,  whatever  may  be  the  resistance  of  the  circuit,  and 
consequently  they  are  not  effaced  by  the  distance  which  divides 
the  two  telephones. 

Experiments  on  the  Part  taken  by  the  Different  Telephonic 
Organs  in  the  Transmission  of  Speech. — In  order  to  introduce 
all  the  improvements  of  which  a  telephone  is  capable,  it  is  im- 
portant to  be  quite  decided  as  to  the  effects  produced  in  the 
several  parts  of  which  it  is  composed,  and  as  to  the  part  taken 
by  the  several  organs  which  are  at  work.  To  attain  this  ob- 
ject several  men  of  science  and  engineers  have  undertaken  a 
series  of  experiments  which  have  produced  very  interesting 
results. 


112  THE    TELEPHONE. 

One  of  the  points  on  -which  it  was  most  important  to  throw 
light  was  that  of  ascertaining  whether  the  vibrating  plate  used 
in  their  telephone  receivers  by  Messrs.  Bell  and  Gray  is  the 
only  cause  of  the  complex  vibrations  which  reproduce  speech, 
or  if  the  different  parts  of  the  electro-magnetic  system  of  the 
instrument  all  conduce  to  this  effect.  The  experiments  made 
by  Mr.  Page  in  1837  on  the  sounds  produced  by  the  resonant 
electro-magnetic  rods,  and  the  researches  pursued  in  1846  by 
Messrs,  de  la  Rive,  Wertheim,  Matteucci,  etc.,  on  this  curious 
phenomenon,  allow  us  to  state  the  question,  which  is  certainly 
more  complex  than  it  at  first  appears. 

In  order  to  start  from  a  fixed  point,  it  must  first  be  ascer- 
tained whether  a  telephone  can  transmit  speech  without  a  vi- 
brating plate.  Experiments  made  by  Mr.  Edison1  in  Novem- 
ber, 1877,  with  telephones  provided  with  copper  diaphragms, 
which  produced  sounds,  make  the  hypothesis  credible;  and 
it  received  greater  weight  from  the  experiments  made  by  Mr. 
Preece  and  Mr.  Blyth.  The  fact  was  placed  beyond  a  doubt 
by  Mr.  Spottiswoode  (see  the  Telegraphic  Journal  of  March 
1st,  1878),  who  assures  us  that  the  vibrating  plate  of  the  tele- 
phone may  be  entirely  suppressed  without  preventing  the 
transmission  of  speech,  provided  that  the  polar  extremity  of 
the  magnet  be  placed  quite  close  to  the  ear ;  and  it  was  after 
this  that  I  presented  to  the  Academic  des  Sciences  my  paper 

1  Mr.  Edison,  in  a  letter  written  November  25th,  1877,  writes  that  he 
has  made  two  telephones  which  act  with  copper  diaphragms,  based  on 
Arago's  effects  of  magnetism  by  rotation.  He  ascertained  that  a  copper 
diaphragm  might  replace  the  iron  plate,  if  its  thickness  did  not  exceed  one 
thirty-second  of  an  inch.  The  effect  produced  is  slight  when  the  copper 
diaphragm  is  placed  between  two  corresponding  instruments ;  but  when 
the  sender  only  is  furnished  with  the  copper  diaphragm,  and  the  receiver 
is  arranged  as  usual,  communication  becomes  easy. 

Mr.  Preece  repeated  these  experiments,  but  he  only  obtained  very  slight 
and  indistinct  effects :  lie  consequently  believes  that  they  are  of  no  prac^ 
tical  use,  although  very  interesting  in  theory. 


MILLAK   TELEPHONE.  113 

on  tlie  theory  of  the  telephone,  which  led  to  an  interesting  dis- 
cussion of  which  I  shall  speak  presently.  At  first  the  authen- 
ticity of  these  results  was  denied,  and  then  an  attempt  was 
made  to  explain  the  sounds  heard  by  Mr.  Spottiswoode  as  a  me- 
chanical transmission  of  the  vibrations,  effected  after  the  man- 
ner of  string  telephones ;  but  the  numerous  experiments  which 
have  subsequently  been  made  by  Messrs.  Warwick,  Rossetti, 
Hughes,  Millar,  Lloyd,  Buchin,  Canestrelli,  Wiesendanger,  Var- 
ley,  and  many  others,  show  that  this  is  not  the  case,  and  that  a 
telephone  without  a  diaphragm  can  transmit  speech  electrically. 

Colonel  ISTavez  himself,  who  had  first  denied  the  fact,  now 
admits  that  a  telephone  without  a  diaphragm  can  emit  sounds, 
and  even,  under  certain  exceptional  conditions,  can  reproduce 
the  human  voice;  but  he  still  believes  that  it  is  impossible  to 
distinguish  articulate  words. 

This  uncertainty  as  to  the  results  obtained  by  the  different 
physicists  who  have  studied  the  matter  shows  that  at  any  rate 
the  sounds  thus  reproduced  are  not  clearly  defined,  and  that  in 
physical  phenomena,  only  appreciable  to  our  senses,  the  appre- 
ciation of  an  effect  so  undefined  must  depend  on  the  perfection 
of  our  organs.  We  shall  presently  see  that  this  very  slight 
effect  can  be  largely  increased  by  the  arrangement  adopted  by 
Messrs.  Bell  and  Gray,  and  we  shall  also  see  that,  by  a  certain 
mode  of  magnifying  the  vibrations,  it  has-  been  decisively 
proved  that  a  telephone  without  a  diaphragm  can  readily  re- 
produce speech.  I  proceed  to  give  the  description  of  such  a 
telephone,  which  was  shown  by  Mr.  Millar  at  the  meeting  of 
the  British  Association  at  Dublin  in  August,  1878. 

This  instrument  consists  of  a  small  bar  magnet,  three  inches 
in  length  and  five-sixteenths  of  an  inch  in  width  and  thick- 
ness, and  a  copper  helix  (No.  30)  of  about  six  metres  in  length 
is  wound  round  the  bar.  It  is  fixed  in  a  box  of  rather  thick 
pasteboard,  fitted  above  and  below  with  two  zinc  plates,  which 
render  it  very  portable.  With  a  telephonic  battery  sender  and 


114  THE    TELEPHONE. 

a  single  Leclanche  cell,  speech  can  be  perfectly  transmitted;  the 
whistling  of  an  air,  a  song,  and  even  the  act  of  respiration  be- 
come audible.  It  seems  also  that  the  instrument  can  act  with- 
out a  magnet,  merely  with  a  piece  of  iron  surrounded  by  the 
helix ;  but  the  sounds  are  then  much  fainter. 

Signer  Ignace  Canestrelli  obtained  the  same  results  by  mak- 
ing one  of  the  carbon  telephonic  senders  react  on  a  telephone 
without  a  diaphragm,  by  means  of  an  induction  coil  influenced 
by  two  Bunsen  cells.  He  writes  as  follows  on  the  subject : 

"With  this  arrangement  I  was  able  to  hear  the  sound  of  any 
musical  instrument  on  a  telephone  without  a  diaphragm :  sing- 
ing, speaking,  and  whistling  were  perfectly  audible.  Whistling 
could  be  heard,  even  when  the  telephone  without  a  diaphragm 
was  placed  at  some  distance  from  the  ear.  In  some  cases,  de- 
pending on  the  pitch  of  the  voice,  on  the  distance  of  the  send- 
ing-station,  and  on  the  joint  pressure  exerted  by  the  carbons,  I 
could  even  distinguish  words. 

"  I  finally  discharged  the  currents  of  the  transmitter  into  the 
coils  of  insulated  copper  wire  with  which  the  two  poles  of  a 
magnet  were  provided.  This  magnet  was  placed  on  a  musical 
box,  made  of  very  thin  slips  of  wood,  and  on  placing  the  ear  at 
the  opening  of  the  box  I  obtained  the  same  results  as  with  the 
ordinary  telephones  without  a  diaphragm." 

M.  Buchin,  after  repeating  experiments  of  the  same  kind  as 
the  above,  intimates  that  it  is  easy  to  hear  the  sounds  produced 
by  a  telephone  without  a  diaphragm,  by  introducing  into  the 
ear  the  end  of  an  iron  rod,  of  which  the  other  end  is  applied 
to  the  active  pole  of  the  bar  magnet  of  the  telephone.  (Sec 
Le  Journal  tfElectrkite,  October  5th,  1878.) 

I  repeat  finally  the  account  of  some  experiments  made  by 
Mr.  Hughes  and  M.  Paul  Roy  which  are  interesting  from  our 
present  point  of  view. 

1.  If  an  armature  of  soft  iron  is  applied  to  the  poles  of  an 
electro-magnet,  with  its  two  branches  firmly  fixed  on  a  board, 


HUGHES  S    EXPERIMENTS.  115 

and  if  pieces  of  paper  are  inserted  between  this  armature  and 
the  magnetic  poles,  so  as  to  obviate  the  effects  of  condensed 
magnetism  ;  if,  finally,  this  electro-magnet  is  connected  with  a 
speaking  microphone,  of  the  form  given  in  Fig.  39,  it  is  possi- 
ble to  hear  the  words  spoken  in  the  microphone  on  the  board 
which  supports  the  electro-magnet. 

2.  If  two  electro-magnets  are  placed  in  communication  with 
a  microphone,  with  their  poles  of  'contrary  signs  opposite  to 
each  other,  and  if  their  poles  are  separated  by  pieces  of  paper, 
speech  will  be  distinctly  reproduced,  without  employing  arma- 
ture or  diaphragm.     These  experiments  are,  however,  delicate, 
and  demand  a  practised  ear. 

3.  If,  instead  of  causing  the  current  produced  by  a  micro- 
phone to  pass  through  the  helix  of  a  receiving  telephone,  it 
is  sent  directly  into  the  bar  magnet  of  this  telephone  in  the 
direction  of  its  axis — that  is,  from  one  pole  to  another — the 
words  pronounced  in  the  microphone  may  be  distinctly  heard. 
This  experiment  by  M.  Paul  Roy  indicates,  if  it  is  exact,  that 
the  electric  pulsations  which  traverse  a  magnet  longitudinally 
will  modify  its  magnetic  intensity.     The  experiment,  however, 
demands  verification. 

Another  point  was  obscure.  It  was  important  to  know 
whether  the  diaphragm  of  a  telephone  really  vibrates,  or  at 
least  if  its  vibrations  could  involve  its  displacement,  such  as 
occurs  in  an  electric  vibrator,  or  in  wind-instruments  which 
vibrate  with  a  current  of  air.  M.  Autoine  Breguet  has  made 
some  interesting  experiments  on  the  subject,  which  show  that 
such  a  movement  cannot  take  place,  since  speech  was  repro- 
duced with  great  distinctness  from  telephones  with  vibrating 
plates  of  various  degrees  of  thickness,  and  he  carried  the  ex- 
periment so  far  as  to  employ  plates  fifteen  centimetres  in  thick- 
ness.1 When  pieces  of  wood,  caoutchouc,  and  other  substances 

1  Mr.  Bell  had  previously  made  a  like  experiment,  which  suggested  to 


116  THE    TELEPHONE. 

were  laid  upon  these  thick  plates,  the  results  were  the  same. 
In  this  case  it  cannot  be  supposed  that  the  plates  were  moved 
to  and  fro.  I  have,  moreover,  ascertained,  by  placing  a  layer 
of  water  or  of  mercury  on  these  plates,  and  even  on  thin  dia- 
phragms, that  no  sensible  movement  took  place,  at  least  when 
the  induced  currents  produced  by  the  action  of  speaking  were 
used  as  the  electric  source.  No  ripples  could  be  seen  on  the 
surface  of  the  liquid,  even  when  luminous  reflectors  were  em- 
ployed to  detect  them.  And  indeed  it  can  hardly  be  admitted 
that  a  current  not  more  intense  than  that  of  a  Daniell  element, 
which  has  traversed  10,000,000  kilometres  of  telegraphic  wire 
— a  current  which  can  only  show  deviation  on  a  Thomson  gal- 
vanometer— should  be  powerful  enough  to  make  an  iron  plate 
as  tightly  stretched  as  that  of  a  telephone  vibrate  by  attrac- 
tion, even  if  we  grant  that  the  current  was  produced  by  laying 
a  finger  on  the  diaphragm. 

Very  nice  photographic  experiments  do,  however,  show  that 
vibrations  are  produced  on  the  *  diaphragm  of  the  receiving 
telephone ;  they  are,  indeed,  excessively  slight,  but  Mr.  Blake 
asserts  that  they  are  enough  to  cause  a  very  light  index,  rest- 
ing on  the  diaphragm,  to  make  slight  inflections  on  a  line 
which  it  describes  on  a  register.  Yet  this  small  vibration  of 
the  diaphragm  does  not  show  that  it  is  due  to  the  effect  of 
attraction,  for  it  may  result  from  the  act  of  magnetization  itself 
in  the  centre  of  the  diaphragm.1  An  interesting  experiment 

him  that  molecular  vibrations  had  as  much  to  do  with  the  action  of  the 
telephone  as  mechanical  vibrations. 

1  M.  Bosscha,  who  has  published  in  the  Archives  Neerlandaises  an  inter- 
esting paper  on  the  intensity  of  electric  currents  in  the  telephone,  says 
that  the  minimum  intensity  of  currents  necessary  to  produce  a  sound  in  a 
telephone  by  the  vibration  of  its  diaphragm  may  be  less  than  -iVz/V  of  a 
Daniell  element,  and  the  displacement  of  the  centre  of  the  diaphragm 
would  then  be  invisible.  He  was  unable  to  measure  exactly  the  range  of 
movements  produced  in  the  diaphragm  by  the  influence  of  the  voice,  but 


ROY'S    EXPERIMENTS.  117 

by  Mr.  Hughes,  repeated  under  different  conditions  by  Mr. 
Millar,  confirms  this  opinion. 

If  the  magnet  of  a  receiving  telephone  consists  of  two 
magnetized  bars,  perfectly  equal,  separated  from  each  other  by 
a  magnetic  insulator,  and  they  are  so  placed  in  the  coil  as  to 
bring  alternately  the  poles  of  the  same  and  of  contrary  signs 
opposite  to  the  diaphragm,  it  is  known  that  the  telephone  will 
reproduce  speech  better  in  the  latter  case  than  in  the  former. 
Now,  if  the  effects  were  due  to  attraction,  this  would  not  be 
the  case ;  for  the  actions  are  in  disagreement  when  the  poles 
of  contrary  signs  are  subjected  to  the  same  electric  influence, 
while  they  are  in  agreement  when  these  poles  are  of  like  signs. 

On  the  other  hand,  it  is  known  that  if  several  iron  plates 
are  put  together  in  order  to  form  the  diaphragm  of  the  re^ 
ceiver,  the  transmission  of  sounds  is  much  stronger  than  with 
a  simple  diaphragm  ;  and  yet  the  attraction,  if  it  has  any- 
thing to  do  with  it,  could  only  be  exerted  on  one  of  the  dia- 
phragms. 

It  further  appears  that  it  is  not  merely  the  magnetic  core 
which  emits  sounds,  but  that  they  are  also  produced  with  some 
distinctness  by  the  helices.  Signor  Rossetti  had  already  ascer- 
tained this  fact,  and  had  even  remarked  that  they  could  be 
animated  by  a  slight  oscillatory  movement  along  the  bar 
magnet,  when  they  were  not  fixed  upon  it.  Several  observers, 
among  others  M.  Paul  Roy,  Herr  Wiesendanger,  and  Signor 
Canestrelli,  have  since  mentioned  similar  facts,  which  are  really 
interesting. 

"  If,"  writes  M.  Paul  Roy,  "  a  coil  of  fine  wire,  which  is  at  the 
extremity  of  the  bar  magnet  of  a  Bell  telephone,  receives  the 


he  believes  it  to  be  less  than  the  thousandth  part  of  a  millimetre ;  and 
from  this  it  follows  that,  for  a  sound  of  880  vibrations,  the  intensity  of  the 
induced  currents  developed  would  be  0.0000v92  of  the  unit  of  electro- 
magnetic intensity. 


118  THE    TELEPHONE. 

pulsatory  currents  transmitted  by  a  carbon  telephone,  it  is 
only  necessary  to  bring  the  coil  close  to  the  ear  in  order  to 
hear  the  sounds. 

"The  sounds  received  in  this  way  are  very  faint,  but  be- 
come much  stronger  if  a  piece  of  iron  is  introduced  into  the 
circuit  coil.  A  magnet  acts  with  still  greater  force,  even  when 
it  consists  of  a  simple  magnetized  needle.  Finally,  the  sound 
assumes  its  maximum  intensity  when  an  iron  disk  is  inserted 
between  the  ear  and  the  coil. 

"  By  placing  the  end  of  the  coil  to  the  ear,  and  sending  a 
current  through  it  from  the  bar  magnet,  it  is  ascertained  that 
the  sound  is  at  its  minimum  when  the  neutral  line  of  the 
magnet  is  enclosed  by  the  coil,  and  that  it  increases  until  at- 
taining its  maximum,  when  the  magnet  is  moved  until  one  of 
its  poles  corresponds  to  the  coil. 

"  This  fact  of  the  reproduction  of  sounds  by  a  helix  is  uni- 
versal. Every  induction  coil  and  every  electro -magnet  are 
capable  of  reproducing  sound  when  the  currents  of  the  sender 
are  of  sufficient  intensity." 

Signor  Canestrelli  writes  as  follows :  "  With  the  combina- 
tion of  a  carbon  telephone  and  one  without  diaphragm  or 
magnet — that  is,  with  only  a  simple  coil — I  was  able  to  hear 
whistling  through  the  coil,  placed  close  to  the  ear.  This  coil 
was  of  very  fine  copper  wire,  and  the  currents  were  produced 
through  an  induction  coil  by  two  Bunsen  elements.  The  con- 
tacts of  the  telephone  were  in  carbon,  and  it  was  inserted  in 
the  primary  circuit. 

"  I  fastened  the  coil  to  the  middle  of  a  tightly  stretched 
membrane  which  served  as  the  base  of  a  short  metal  cylinder. 
When  a  magnet  was  placed  near  this  part  of  the  coil,  the 
sounds  were  intensified,  and  when  I  fixed  the  magnet  in  this 
position,  I  could  hear  what  was  said. 

"  I  afterward  substituted  for  the  magnet  a  second  coil,  fast- 
ened to  a  wooden  bar,  and  on  causing  the  induced  currents  to 


LUVINIS    EXPERIMENTS.  119 

pass  into  both  coils  at  once  I  was  able  to  hear   articulate 
speech,  although  not  without  difficulty. 

"  Under  these  latter  conditions  I  found  it  possible  to  con- 
struct a  telephone  without  a  magnet,  but  it  required  a  strong 
current,  and  it  was  necessary  to  speak  into  the  sender  in  a  spe- 
cial manner,  so  as  to  produce  strong  and  concentrated  sounds." 

Another  very  interesting  experiment  by  M.  A.  Breguet  shows 
that  all  the  constituent  parts  of  the  telephone  —  the  handle, 
the  copper  rims,  and  the  case,  as  well  as  the  diaphragm  and  the 
electro-magnet — can  transmit  sounds.  M.  Breguet  ascertained 
this  fact  by  the  use  of  string  telephones,  which  he  attached  to 
different  parts  of  the  telephone  on  which  the  experiment  was 
made.  In  this  way  he  was  not  only  able  to  establish  a  corre- 
spondence between  the  person  who  worked  the  electric  tele- 
phone and  the  one  who  was  listening  through  the  string  tele- 
phone, but  he  also  made  several  string  telephones  act,  which 
were  attached  to  different  parts  of  the  electric  telephone. 

These  two  series  of  experiments  show  that  sounds  may  be 
obtained  from  different  parts  of  the  telephone  without  any 
very  appreciable  vibratory  movements.  But  Signor  Luvini 
wished  for  a  further  assurance  of  the  fact,  by  ascertaining 
whether  the  magnetization  of  any  magnetic  substance,  followed 
by  its  demagnetization,  would  involve  a  variation  in  the  form 
arid  dimensions  of  this  substance.  He  consequently  caused  a 
large  tubular  electro-magnet  to  be  made,  which  he  filled  with  a 
quantity  of  water,  so  that,  when  its  two  ends  were  corked,  the 
liquid  should  rise  in  a  capillary  tube  fitted  to  one  of  the  corks. 
In  this  way  the  slightest  variations  in  the  capacity  of  the  hol- 
low part  of  the  electro-magnet  were  revealed  by  the  ascent  or 
descent  of  the  liquid  column.  He  next  sent  an  electric  current 
of  varying  intensity  through  the  electro-magnet,  but  he  was 
never  able  to  detect  any  change  in  the  level  of  the  water  in 
the  tube ;  although  by  this  arrangement  he  could  measure  a 
change  of  volume  of  one-thirtieth  of  a  cubic  millimetre.  It 


120  THE    TELEPHONE. 

appears  from  this  experiment  that  the  vibrations  produced  in  a 
magnetic  substance  under  the  influence  of  successive  magnetiza- 
tions and  demagnetizations,  are  wholly  molecular.  Yet  other 
experiments  made  by  M.  Canestrelli  seem  to  show  that  these 
vibrations  are  so  far  sensible  as  to  produce  sounds  which  can 
be  detected  by  the  microphone.  He  writes  as  follows  on  the 
subject : 

"When  the  broken  currents  of  an  induction  coil  are  dis- 
charged into  a  coil  placed  on  a  sounding -box,  it  is  possible 
to  hear  at  a  little  distance  the  sounds  produced  by  the  induced 
currents  thus  generated.  On  approaching  the  magnet  to  the 
opening  of  the  coil,  these  sounds  are  intensified,  and  the  vibra- 
tions of  the  magnet  become  sensible  to  the  touch ;  this  vibra- 
tion might  even  be  made  visible  by  suspending  the  magnet  in- 
serted into  the  coil  to  a  metallic  wire,  which  is  fitted  to  a 
membrane  stretched  on  a  drum,  and  the  latter  will  then  repro- 
duce sounds.  When  the  same  magnet  is  suspended  to  a  mi- 
crophone, it  is  possible,  with  the  aid  of  a  telephone,  to  ascer- 
tain the  same  effects,  which  are  then  increased." 

We  shall  presently  consider  how  these  different  deductions 
are  to  be  interpreted,  so  as  to  render  the  true  theory  of  the 
telephone  intelligible;  but,  before  doing  so,  we  will  mention 
some  other  experiments  which  are  not  without  interest. 

We  have  seen  that  the  experiments  of  Messrs.  Edison,  Blyth, 
and  Preece  show  that  sounds  may  be  reproduced  by  a  tele- 
phone with  a  diaphragm  made  of  some  unmagnetic  substance, 
and  they  also  show,  which  is  still  more  curious,  that  these 
sounds  may  be  transmitted  under  the  influence  of  induced  cur- 
rents produced  by  these  diaphragms  when  they  are  placed  in 
vibration  before  the  magnet.  Messrs.  Edison  and  Blyth  had 
already  adduced  this  fact,  which  was  received  with  incredulity, 
but  it  has  been  confirmed  by  Mr.  Warwick  in  an  article  pub- 
lished in  the  English  Mechanic.  He  writes  that  in  order  to 
act  upon  the  magnet,  so  as  to  produce  induced  currents,  some- 


EXPERIMENTS.  121 

thing  possessed  of  greater  energy  than  gas  must  first  be  made 
to  vibrate.  It  is  not,  however,  necessary  that  this  substance 
should  be  magnetic,  for  diamagnetic  substances  act  perfectly.1 

1  Mr.  Warwick  describes  his  experiments  as  follows :  "  The  magnets 
employed  were  nearly  of  the  usual  size,  one  inch  and  a  half  in  diameter, 
and  nearly  eight  times  as  long.  At  first  I  employed  iron  disks,  but  I  found 
them  to  be  unnecessary.  When  I  had  discarded  them,  I  tried  several  sub- 
stances :  first  a  thin  disk  of  iron,  which  answered  perfectly  both  for  sender 
and  receiver.  A  disk  of  sheet-iron,  about  one-tenth  of  an  inch  in  thick- 
ness,  did  not  act  so  well,  but  all  that  was  said  was  quite  understood.  In 
making  experiments  with  the  disks,  I  simply  placed  them  above  the  instru- 
ment, without  fixing  them  in  any  way :  the  wooden  cover  and  the  conical 
cavity  were  also  laid  aside,  because  the  transmission  and  reception  could 
be  effected  as  well  without  them.  This  .part  of  the  instrument  seems  to 
be  superfluous,  since,  when  the  disk  is  simply  placed  level  to  the  ear,  the 
sound  seems  to  be  increased  by  being  brought  nearer.  Although  iron  acts 
better  than  anything,  it  appears  that  iron  disks  are  not  absolutely  neces- 
sary, and  that  diamagnetic  substances  also  act  perfectly.  I  wished  that 
my  assistant,  who  was  at  some  distance,  and  could  not  hear  any  direct 
sound,  should  continue  his  calculations.  I  took  away  the  iron  disk  and 
placed  across  the  instrument  a  wide  iron  bar  an  inch  thick.  On  applying 
my  ear  to  it,  I  could  hear  every  sound  distinctly,  but  somewhat  more  faint- 
ly. A  piece  of  copper,  three  inches  square,  was  substituted  for  it :  al- 
though the  sound  was  still  distinct,  it  was  fainter  than  before.  Thick 
pieces  of  lead,  zinc,  and  steel  were  alternately  tried.  The  steel  acted  in 
almost  the  same  way  as  the  iron,  and,  as  in  the  other  cases,  each  word  was 
heard  faintly  but  distinctly.  Some  of  these  metals  are  diamagnetic,  and 
yet  the  action  took  place.  Some  non-metallic  substances  were  next  tried  ; 
first  a  piece  of  window-glass,  w^hich  acted  very  well.  The  action  was  faint 
with  a  piece  of  a  wooden  match-box ;  but  on  using  pieces  of  gradually  in- 
creasing thickness  the  sound  was  sensibly  increased,  and  with  a  piece  of 
solid  wood,  one  inch  and  a  half  in  thickness,  the  sound  was  perfectly  dis- 
tinct. I  next  replaced  it  by  an  empty  wooden  box,  which  acted  very  well. 
A  piece  of  cork,  half  an  inch  thick,  acted,  but  somewhat  faintly.  A  block 
of  razor-stone,  two  inches  thick,  was  placed  upon  the  instrument,  and,  on 
applying  the  ear  to  it,  it  was  quite  easy  to  follow  the  speaker.  I  then 
tried  to  hear  without  the  insertion  of  any  substance,  and,  on  applying  my 
ear  quite  close  to  the  coil  and  magnet,  I  heard  a  faint  sound,  and  on  listen- 

G 


122  THE    TELEPHONE. 

Mr.  Preece  sought  for  the  cause  in  the  induced  currents  devel- 
oped in  any  conducting  body  when  a  magnet  is  moved  before 
it,  currents  which  give  rise  to  the  phenomenon  discovered  by 
Arago,  and  known  by  the  name  of  magnetism  by  rotation. 
Yet  these  facts  do  not  appear  to  us  to  be  sufficiently  well  es- 
tablished to  make  the  theory  worthy  of  serious  consideration, 
and  it  is  possible  that  the  effects  observed  resulted  from  simple 
mechanical  transmissions. 

To  conclude  the  account  of  these  experiments,  we  will  add 
that  Mr.  W.  F.  Barrett  thinks  it  somewhat  difficult  to  define 
the  mode  of  vibration  of  the  diaphragm,  since,  while  a  certain 
amount  of  compression  exerted  on  the  iron  destroys  the  sounds 
resulting  from  the  peculiar  effects  of  magnetization,  a  still 
stronger  compression  causes  them  to  reappear.  It  is  certain 

ing  attentively  I  understood  all  that  was  said.  In  all  these  experiments 
the  sounds  were  perceived,  but  the  sounds  transmitted  or  attempted  did 
not  act  precisely  alike.  The  sound  of  a  tuning-fork,  placed  on  the  iron 
disk  itself  or  on  the  case  of  the  instrument,  was  clearly  heard  :  thin  iron 
disks  were  more  effective  for  articulate  speech.  With  other  substances, 
stone,  solid  wood,  glass,  zinc,  etc.,  the  sound  of  the  tuning-fork  was  heard, 
whether  it  rested  upon  them,  or  the  vibrating  fork  was  held  above  them. 
These  substances  were  not  adapted  for  transmitting  the  sound  of  the 
voice.  These  were  all  laid  aside,  and  the  sounding  instrument  was  held 
directly  above  the  pole  of  the  magnet :  the  sound  was  clearly  heard,  al- 
though there  was  nothing  but  air  between  the  end  of  the  magnet  and  the 
tuning-fork.  The  sound  was  perhaps  less  intense  when  the  tuning-fork 
was  held  directly  above  the  pole  than  when  it  was  at  the  end  of  the  mag- 
net. I  next  tried  if  my  voice  could  be  heard  with  this  arrangement.  The 
result  was  rather  doubtful,  but  I  think  that  some  action  must  have  taken 
place,  for  the  tuning-fork  was  heard  when  it  was  simply  vibrated  near  the 
pole.  The  effect  of  the  voice  can  only  have  differed  in  the  degree  of  in- 
tensity :  it  was  too  faint  to  be  heard  at  the  other  extremity.  I  repeated 
these  effects  ;  I  assured  myself  of  them,  and  I  succeeded  in  transmitting 
sounds  distinctly  on  the  pole  without  a  disk,  and,  on  the  other  hand,  by 
applying  my  ear  to  the  instrument,  I  was  able  to  hear  distinctly  all  that 
was  said,  although  there  was  no  disk." 


DES    PORTES'S    EXPERIMENTS.  123 

that  the  question  is  full  of  obscurity,  and  demands  great  re- 
search :  it  is  enough  to  have  shown  that  the  theory  hitherto 
held  is  insufficient. 

On  the  other  hand,  Colonel  Navez  considers  that  the  inten- 
sity of  sound  reproduced  in  a  telephone  depends  not  only  on 
the  range  of  vibrations,  but  also  on  the  vibrating  surface  and 
the  effect  it  produces  on  the  stratum  of  air  which  transmits 
the  sound.  (See  paper  by  Colonel  Navez  in  the  Bulletin  de 
VAcademie  de  Belyique,  July  7th,  1878.) 

Experiments  on  the  Effects  which  result  from  Mechanical 
Shocks  communicated  to  different  parts  of  a  Telephone. — If  a 
piece  of  iron  is  applied  to  the  screw  which  holds  the  magnet 
of  the  ordinary  telephone,  it  is  observed  that  the  transmitted 
sounds  are  more  distinct,  owing  to  the  force  supplied  to  the 
active  pole  of  the  magnet ;  but  at  the  moment  when  the  piece 
of  iron  is  applied  to  the  screw  a  distinct  noise  is  heard,  which 
seems  to  be  due  to  the  mechanical  vibrations  caused  in  the 
magnet  at  the  moment  of  the  shock.  M.  des  Fortes,  a  lieuten- 
ant in  the  French  navy,  has  lately  made  some  interesting  ex- 
periments on  this  class  of  phenomena.  He  has  observed  that 
if,  in  a  telephonic  circuit  of  ninety  yards  completed  by  the 
earth,  the  sending  telephone  is  reduced  to  a  simple  magnet, 
provided  with  the  coil  which  constitutes  its  electro-magnetic 
organ,  and  if  this  magnet  is  suspended  vertically  by  a  silken 
thread,  with  the  coil  above  it,  a  blow  struck  upon  the  magnet, 
either  by  a  copper  rod  or  a  piece  of  wood,  will  cause  distinct 
sounds  to  be  produced  in  the  receiving  telephone  —  sounds 
which  will  increase  in  intensity  when  the  blow  is  struck  close 
to  the  coil,  and  which  will  become  still  stronger,  but  less  clear, 
if  a  vibrating  plate  of  soft  iron  is  placed  in  contact  with  the 
upper  pole  of  the  magnet. 

"When  the  striking  instrument  is  made  of  iron,  the  sounds 
in  question  are  more  strongly  marked  than  if  it  is  of  wood; 
and  when  the  magnet  has  a  vibrating  disk  applied  to  its  active 


124  THE    TELEPHONE. 

pole,  a  vibration  of  the  disk  takes  place  at  the  moment  when 
the  shock  is  heard. 

If  the  striking  body  is  a  magnet,  the  sounds  produced  re- 
semble those  obtained  when  it  is  of  iron,  if  the  effect  is  pro- 
duced between  poles  of  the  same  nature ;  but  if  the  poles  are 
of  contrary  natures,  a  second  noise  is  heard  after  each  blow, 
which  is  produced  by  drawing  away  the  magnet,  and  which  ap- 
pears to  be  a  blow  struck  with  much  less  force.  The  sound  is  of 
course  increased  if  the  magnet  is  provided  with  its  vibrating  disk. 

If  words  are  uttered  on  the  vibrating  disk  of  the  sending 
telephone,  when  it  is  applied  to  the  pole  of  the  magnet,  various 
sounds  are  heard  on  the  receiving  telephone,  somewhat  similar 
to  those  produced  by  vibrating  one  of  the  strings  of  a  violin, 
and  the  sound  made  in  withdrawing  the  disk  from  contact  with 
the  magnet  is  distinctly  heard  in  the  receiver. 

The  person  who  applies  his  ear  to  the  vibrating  disk  of  the 
sender  when  it  is  arranged  as  above,  may  hear  the  voice  of 
any  one  who  speaks  into  the  receiver,  but  cannot  distinguish 
the  words,  owing,  no  doubt,  to  the  condensed  magnetism  at  the 
point  of  contact  between  the  magnet  and  the  vibrating  disk, 
which  slackens  the  magnetic  variations,  and  makes  it  more 
difficult  for  them  to  take  place. 

A  coil  is  not  necessary  in  order  to  perceive  the  blows  struck 
upon  the  magnet  with  a  rod  of  soft  iron.  It  is  enough  to  wind 
three  turns  of  naked  conducting  wire,  which  acts  as  line  wire, 
round  one  end  of  the  magnet,  and  the  sounds  perceived  cease, 
as  in  other  experiments,  when  the  circuit  is  broken,  plainly 
showing  that  they  are  not  due  to  mechanical  transmission.  It 
is  a  still  more  curious  fact  that  if  the  magnet  is  placed  in  the 
circuit,  so  as  to  form  an  integral  part  of  it,  and  if  the  two  ends 
of  the  conducting  wire  are  wound  round  the  ends  of  the  mag- 
net, the  blows  struck  upon  the  latter  with  the  soft  iron  rod  are 
perceived  in.  the  telephone  as  soon  as  one  pole  of  the  magnet 
is  provided  with  a  vibrating  disk. 


THOMPSON'S  EXPERIMENTS.  125 

I  have  myself  repeated  M.  des  Portes's  experiments  by  sim- 
ply striking  on  the  screw  which,  in  ordinary  telephones,  fastens 
the  magnet  to  the  instrument,  and  I  have  ascertained  that, 
whenever  the  circuit  was  complete,  the  blows  struck  with  an 
ivory  knife  were  repeated  by  the  telephone  :  they  were,  it  is 
true,  very  faint  when  the  vibrating  disk  was  removed,  but  very 
marked  when  the  disk  was  in  its  place.  On  the  other  hand, 
no  sound  was  perceived  when  the  circuit  was  broken.  These 
sounds  were  louder  when  the  blows  were  struck  upon  the  screw 
than  when  they  were  struck  on  the  pole  of  the  magnet  itself 
above  the  coil :  for  this  reason,  that  in  the  first  case  the  mag- 
net could  vibrate  freely,  while  in  the  second  the  vibrations  were 
stifled  by  the  fixed  position  of  tha  bar  magnet. 

These  effects  may  be  to  some  extent  explained  by  saying 
that  the  vibrations  caused  in  the  magnet  by  the  shock  pro- 
duce undulatory  displacements  of  the  magnetized  particles  in 
the  whole  length  of  the  bar,  and  that  induced  currents  would, 
according  to  Lenz's  law,  result  in  the  helix  from  these  displace- 
ments—  currents  of  which  the  force  would  increase  when  the 
power  of  the  magnet  was  further  excited  by  the  reaction  of 
the  diaphragm,  which  acts  as  an  armature,  and  also  by  that 
of  the  striking  instrument  when  it  also  is  magnetic.  Yet  it  is 
more  difficult  to  explain  M.  des  Portes's  later  experiments,  and 
the  effect  may  be  produced  by  something  more  than  the  or- 
dinary induced  currents. 

These  are  not  the  only  experiments  which  show  the  effects 
produced  under  the  influence  of  molecular  disturbance  of  vari- 
ous kinds.  Mr.  Thompson,  of  Bristol,  has  observed  that  if  a 
piece  of  iron  and  a  tin  rod  placed  perpendicularly  on  the  iron 
are  introduced  into  the  circuit  of  an  ordinary  telephone,  it  is 
enough  to  strike  the  tin  rod  in  order  to  produce  a  loud  sound 
in  the  telephone.  He  has  also  shown  that  if  the  two  ends  of 
a  bar  magnet  arc  enclosed  by  two  induction  coils  which  are 
placed  in  connection  with  the  circuit  of  a  telephone,  and  if  the 


126  THE    TELEPHONE. 

flame  of  a  spirit-lamp  is  moved  below  the  magnet  in  the  space 
dividing  the  two  coils,  a  distinct  sound  is  heard  as  soon  as  the 
flame  exerts  its  influence  on  the  bar  magnet.  This  effect  is 
undoubtedly  due  to  the  weakening  of  the  magnetic  force  of 
the  bar  which  is  produced  by  the  action  of  heat.  I  have  my- 
self observed  that  a  scratching  sound  on  one  of  the  wires  which 
connect  the  telephones  is  heard  in  both  of  them,  at  whatever 
point  in  the  circuit  the  scratch  is  made.  The  sounds  produced 
are  indeed  very  faint,  but  they  can  be  distinctly  heard,  and 
they  become  more  intense  when  the  scratch  is  made  on  the 
binding-screws  of  the  telephone  wires.  These  sounds  cannot 
result  from  the  mechanical  transmission  of  vibrations,  since 
they  are  imperceptible  when  the  circuit  is  broken.  From  these 
experiments  it  appears  that  some  sounds  which  have  been  ob- 
served in  telephones  tried  on  telegraph  stations  may  arise  from 
the  friction  of  the  wires  on  their  supports — a  friction  which 
produces  those  very  intense  sounds  which  are  sometimes  heard 
on  telegraphic  wires. 

Theory  of  the  Telephone. — It  appears  from  the  several  ex- 
periments of  which  we  have  spoken  that  the  explanation  gen- 
erally given  of  the  effects  produced  in  the  telephone  is  very 
imperfect,  and  that  the  transmission  of  speech,  instead  of  re- 
sulting from  the-  repetition  by  the.  membrane  of  the  receiv- 
ing telephone  (influenced  by  electro-magnetism)  of  vibrations 
caused  by  the  voice  on  the  membrane  of  the  transmitting 
membrane,  is  due  to  molecular  vibrations  produced  in  the 
whole  electro-magnetic  system,  and  especially  on  the  magnetic 
core  contained  in  the  helix.  These  vibrations  must  be  of  the 
same  nature  as  those  which  have  been  observed  in  resonant 
electro-magnetic  rods  by  MM.  Page,  de  la  Rivc,Wertheim,  Mat- 
tcucci,  etc.,  and  these  have  been  employed  in  telephones  by 
Reiss,  by  Cecil  and  Leonard  Wray,  and  by  Vanderwcyde. 

According  to  this  hypothesis,  the  principal  office  of  the  vi- 
brating plate  consists  in  its  reaction,  in  order  to  produce  the 


DE   LA   KITE'S    OPINION.  127 

induced  currents  when  the  voice  has  placed  it  in  vibration,  and 
by  this  reaction  on  the  polar  extremity  of  the  bar  magnet  it 
strengthens  the  magnetic  effects  caused  in  the  centre  of  the 
bar  when  it  vibrates  under  the  electro-magnetic  influence,  or  at 
least  when  it  is  affected  by  the  magnet.  Since  the  range  of 
these  vibrations  for  a  single  note  is  great  in  proportion  to  the 
flexibility  of  the  note,  and  since,  on  the  other  hand,  the  varia- 
tions in  the  magnetic  condition  of  the  plate  are  rapid  in  pro- 
portion to  the  smallness  of  its  mass,  the  advantage  of  employ- 
ing, as  Mr.  Edison  has  done,  very  thin  and  relatively  small 
plates  is  readily  understood.  In  the  case  of  transmission,  the 
wider  range  of  vibration  increases  the  intensity  of  the  induced 
currents  transmitted.  In  the  case  of  reception  the  variations 
in  the  magnetizing  force  which  produces  the  sounds  are  ren- 
dered clearer  and  more  distinct,  both  in  the  armature  mem- 
brane and  in  the  bar  magnet :  something  is  gained,  therefore, 
in  each  case.  This  hypothesis  by  no  means  excludes  the  pho- 
netic effects  of  the  mechanical  and  physical  vibrations  which 
may  be  produced  in  the  armature  plate  under  the  influence  of 
magnetization  and  demagnetization  to  which  it  is  subjected, 
and  these  join  their  influence  to  that  of  the  magnetic  core. 

What  is  the  nature  of  the  vibrations  sent  into  the  receiving 
telephone  ?  This  question  is  still  obscure,  and  those  who  have 
studied  it  are  far  from  being  in  agreement :  as  early  as  1846  it 
was  the  subject  of  an  interesting  discussion  between  MM.Wert- 
lieim  and  de  la  Rive,  and  the  new  discoveries  render  it  still 
more  complex.  M.  Wertheim  considers  that  these  vibrations 
are  at  once  longitudinal  and  transverse,  and  arise  from  attrac- 
tions exchanged  between  the  spirals  of  the  magnetizing  helix 
and  the  magnetic  particles  of  the  core.  M.  de  la  Rive  holds 
that  in  the  case  we  are  considering  the  vibrations  are  simply 
longitudinal,  and  result  from  molecular  contractions  and  ex- 
pansions produced  by  the  different  combinations  assumed  by 
the  magnetic  molecules  under  the  influence  of  magnetization 


128  THE    TELEPHONE. 

and  demagnetization.  This  appears  to  us  to  be  the  most  nat- 
ural explanation,  and  it  seems  to  be  confirmed  by  the  experi- 
ment made  by  M.  Guillemin  in  1846.  M.  Guillemin  ascertained 
that  if  a  flexible  iron  rod,  surrounded  by  a  magnetizing  helix, 
is  kept  in  position  by  a  vise  at  one  end,  arid  bent  back  by  a 
weight  at  the  other,  it  can  be  made  to  return  instantly  to  its 
normal  position  by  sending  a  current  through  the  magnetizing 
helix.  This  recovery  can  in  such  a  case  be  due  to  nothing  but 
the  contraction  caused  by  the  magnetic  molecules,  which,  under 
the  influence  of  their  magnetization,  tend  to  produce  intermo- 
lecular  attractions,  and  to  modify  the  elastic  conditions  of  the 
metal.  It  is  known  that  when  iron  is  thus  magnetized  it  be- 
comes as  hard  as  steel,  and  a  file  makes  no  impression  on  its 
surface. 

It  is,  at  any  rate,  impossible  to  dispute  that  sounds  are  pro- 
duced in  the  magnetic  core,  as  well  as  in  the  armature,  under 
the  influence  of  intermittent  electric  action.  These  sounds 
may  be  musical  or  articulate;  for  as  soon  as  the  sender  has 
produced  the  electric  action  required,  there  is  no  reason  why 
vibrations  which  are  effected  in  a  transverse  or  longitudinal 
direction  should  transmit  the  one  more  than  the  other.  These 
vibrations  may,  as  we  have  seen,  be  termed  microscopic. 

Signor  Luvini,  who  shares  our  opinion  of  the  foregoing  the- 
ory, does  not,  however,  think  it  wholly  satisfactory,  unless  ac- 
count is  taken  of  the  reaction  caused  by  the  bar  magnet  on 
the  helix  which  surrounds  it.  "  There  cannot,"  he  says,  "  be 
action  without  reaction,  and  consequently  the  molecular  action 
produced  in  the  magnet  ought  to  cause  corresponding  varia- 
tions in  the  helix,  and  these  two  effects  ought  to  contribute  to 
the  production  of  sounds."  He  supports  this  remark  by  a  ref- 
erence to  Professor  Rossetti's  experiment,  of  which  we  have 
spoken  above.- 

We  believe,  however,  that  this  double  reaction  of  which 
Signor  Luvini  speaks  is  not  indispensable,  for  we  have  seen 


A 

ACTION   OF  DlAPimAGSfc-'j  /     » 

that  insulated  helices  can  produce  sounds;  it  is  true  itf 
spirals,  reacting  on  each  other,  may  be  the  cause  of  this.          '  „ 

The  difficulty  of  explaining  the  production  of  sounds  in  an 
electro-magnetic  organ  destitute  of  armature  caused  the  authen- 
ticity of  the  experiments  we  have  described  to  be  at  first  de- 
nied, and  Colonel  Navez  started  a  controversy  with  us  which  is 
not  likely  to  be  soon  terminated ;  yet  one  result  of  this  con- 
troversy is  that  Colonel  Navez  was  obliged  to  admit  that  the 
sound  of  the  human  voice  may  be  reproduced  by  a  telephonic  re- 
ceiver without  a  disk.  But  he  still  believes  that  this  reproduc- 
tion is  so  faint  that  it  is  not  possible  to  recognize  articulate 
words,  and  he  maintains  that  the  transverse  vibrations  of  the 
disk,  which  are  due  to  effects  o£  attraction,  are  the  only  ones 
to  reproduce  articulate  speech  with  such  intensity  as  to  be  of 
any  use. 

It  is  certain  that  the  articulation  of  speech  requires  a  some- 
what intense  vibration  which  cannot  easily  be  produced  in  a 
telephone  without  a  diaphragm ;  for  it  must  be  remembered 
that  in  an  instrument  so  arranged,  the  magnetic  effects  are 
reduced  in  a  considerable  ratio,  which  is  that  of  the  magnetic 
force  developed  in  the  magnet,  multiplied  by  itself,  and  that 
so  faint  an  action  as  that  effected  in  a  telephone  becomes  al- 
most null  when,  in  consequence  of  the  suppression  of  the  arma- 
ture, it  is  only  represented  by  the  square  root  of  the  force 
which  produced  it.  It  is  therefore  possible  that  the  sounds 
which  are  hardly  perceptible  in  a  telephone  without  a  dia- 
phragm become  audible  when  the  cause  which  provokes  them 
is  multiplied  by  itself,  and  when  there  are  in  addition  the 
vibrations  produced  in  the  heart  of  the  armature  itself,  in- 
fluenced by  the  magnetizations  and  demagnetizations  to  which 
it  is  subjected. 

In  order  to  show  that  the  action  of  the  diaphragm  is  less 
indispensable  than  Colonel  Navez  seems  to  imagine,  and  that 
its  vibrations  are  not  due  to  electro -magnetic  attractions,  it 

6* 


130  THE    TELEPHONE. 

will  be  enough  to  refer  to  Mr.  Hughes's  experiments,  which 
we  have  mentioned  above.  It  is  certain  that  if  this  were  the 
effect  produced,  we  should  hear  better  when  the  two  bar 
magnets  present  their  poles  of  the  same  nature  before  the  dia- 
phragm, than  when  they  present  the  poles  of  contrary  natures, 
since  the  whole  action  would  then  converge  in  the  same  direc- 
tion. Again,  the  more  marked  effects  obtained  with  multiple 
diaphragms  in  juxtaposition  completely  exclude  this  hypothe- 
sis. It  is,  however,  possible  that  in  electro-magnetic  telephones 
the  iron  diaphragm,  in  virtue  of  the  rapid  variations  of  its  mag- 
netic condition,  may  contribute  to  render  the  sounds  clearer  and 
more  distinct;  it  may  react  in  the  way  the  tongue  does;  but 
we  believe  that  the  greater  or  less  distinctness  of  the  articulate 
sounds  must  be  chiefly  due  to  the  range  of  vibrations.  Thus 
Mr.  Hughes  has  shown  that  the  carbons  of  metallized  wood 
employed  in  his  microphonic  speakers  were  to  be  preferred  to 
retort  carbons  for  the  transmission  of  speech,  for  the  very  rea- 
son that  they  had  less  conductivity,  so  that  the  differences  of 
resistance  which  result  from  differences  of  pressure  are  more 
marked,  and  consequently  it  is  easier  to  seize  the  different 
degrees  of  vocal  sounds  which  constitute  articulate  speech. 

It  must  be  clearly  understood  that  what  we  have  just  said 
only  applies  to  the  Bell  telephone,  that  is,  to  a  telephone  in 
which  the  electric  currents  have  such  a  faint  intensity  that  it 
cannot  be  supposed  there  is  any  external  attractive  effect. 
When  these  currents  are  so  energetic  as  to  produce  such  an 
effect,  a  transverse  electro -magnetic  vibration  certainly  takes 
place,  which  is  added  to  the  molecular  vibration,  and  helps  to 
increase  the  sounds  produced.  But  it  is  no  less  true  that 
this  transverse  vibration  by  attraction  or  by  movement  of  the 
diaphragm  is  not  necessary  for  the  reproduction  of  sounds, 
whether  musical  or  articulate. 

We  are  not  now  concerned  with  the  discussion  of  magnetic 
effects;  there  has  been  an  advance  in  science  since  Colonel 


EFFECTS    OF    REACTION.  131 

Xavez  started  the  controversy,  and  we  must  ask  how  his  theory 
of  the  movements  of  the  telephone  diaphragm  by  attraction 
will  explain  the  reproduction  of  speech  by  a  receiving  micro- 
phone destitute  of  any  electro-magnetic  organ,  and  I  can  assert 
that  my  experiments  show  that  there  can  be  no  mechanical 
transmission  of  vibrations,  since  no  sound  is  heard  when  the 
circuit  is  broken  or  deprived  of  its  battery.  Colonel  Navez 
must  therefore  accept  the  molecular  vibrations.  This  certainly 
gives  us  a  new  field  for  study ;  but  it  is  because  European 
men  of  science  persist  in  remaining  bound  by  incomplete  theo- 
ries that  we  have  allowed  the  Americans  who  despise  them  to 
reap  the  glory  of  the  great  discoveries  by  which  we  have  lately 
been  astonished. 

The  experiments  quoted  above  show  that  sounds  may  be 
reproduced  not  only  by  simple  helices  without  an  electro- 
magnetic organ,  but  also  by  the  plates  of  a  condenser,  in  spite 
of  the  pressure  exerted  upon  them ;  and  when  we  add  to  this 
the  effects  I  have  just  pointed  out,  it  may  be  supposed  that 
vibrations  of  sound  must  result  from  every  reaction  between 
two  bodies  which  has  the  effect  of  producing  abruptly  and  at 
close  intervals  modifications  in  the  condition  of  their  electric 
or  magnetic  equilibrium.  It  is  known  that  the  presence  of 
ponderable  matter  is  necessary  for  the  production  of  electric 
effects,  and  it  is  possible  that  the  molecular  vibrations  of  which 
I  have  spoken  may  be  the  result  of  molecular  movements,  due 
to  the  variations  of  the  electric  force  which  holds  the  mole- 
cules in  a  special  condition  of  reciprocal  equilibrium. 

In  conclusion,  the  theory  of  the  telephone  and  microphone, 
considered  as  reproductive  organs  of  speech,  is  still  far  from 
being  perfectly  clear,  and  it  would  be  imprudent  to  be  too 
positive  on  questions  of  such  recent  origin. 

The  theory  of  the  electric  transmission  of  sounds  in  electro- 
magnetic telephones  is  somewhat  complex.  It  has  been  seen 
that  they  can  be  obtained  from  diaphragms  of  non-magnetic 


132  THE    TELEPHONE. 

substance,  and  even  from  simple  mechanical  vibrations  produced 
by  shocks.  Are  \ve  to  ascribe  them  in  the  first  case  to  the 
inductive  reaction  of  the  magnet  on  the  vibrating  plate,  and  in 
the  second  case  to  the  movements  of  magnetic  particles  before 
the  spirals  of  the  helix  ?  The  matter  is  still  very  obscure ;  yet 
it  is  conceivable  that  the  modifications  of  the  inducing  action 
of  the  magnet  on  the  vibrating  diaphragm  may  involve  varia- 
tions in  the  magnetic  intensity,  just  as  we  can  admit  an  effect 
of  the  same  kind  due  to  the  approach  and  withdrawal  of  the 
magnetic  particles  of  the  spirals  of  the  helix ;  M.  Treve,  how- 
ever, believes  that  there  is  in  the  latter  case  a  special  action, 
which  he  has  already  had  occasion  to  study  under  other  cir- 
cumstances, and  he  sees  in  the  current  thus  caused  the  effect 
of  the  transformation  of  the  mechanical  labor  produced  amidst 
the  magnetic  molecules.  The  question  is  complicated  by  the 
fact  that  these  effects  are  often  produced  by  purely  mechanical 
transmissions. 

There  is  another  point  to  consider,  on  which  Colonel  Navcz 
has  made  some  interesting  remarks;  that  is,  whether  the  effects 
in  the  receiver  are  stronger  with  permanent  than  with  tempo- 
rary magnets.  In  the  first  model  of  the  telephone,  exhibited 
by  Mr.  Bell  at  Philadelphia,  the  receiver  was,  as  I  have  said, 
made  of  a  tubular  electro-magnet,  furnished  with  a  vibrating 
disk  at  its  cylindrical  pole ;  but  this  arrangement  was  aban- 
doned by  Mr.  Bell,  with  the  object,  as  he  states  in  his  paper,  of 
rendering  his  instrument  both  a  receiver  and  a  sender.1  Yet 
Colonel  Navez  maintains  that  the  magnet  plays  an  important 
part,  and  is  even  indispensable  under  the  present  conditions 
of  its  form.  "  It  is  possible,"  he  says,  "  under  certain  circum- 

1  These  are  his  own  words :  "  The  articulation  produced  from  the  instru- 
ment was  remarkably  clear,  but  its  great  defect  consisted  in  the  fact  that 
it  could  not  be  used  as  a  sending  instrument,  and  thus  two  telephones  were 
required  at  each  station,  one  for  transmitting  and  one  for  receiving  spoken 
messages." 


ACTION   OF   CURRENTS.  133 

stances,  and  by  making  the  instrument  in  a  special  way,  to 
make  a  Bell  receiver  speak  without  a  permanent  magnet,  yet 
with  an  instrument  of  the  usual  construction  the  sound  ceases 
when  the  magnet  is  withdrawn  and  replaced  by  a  cylinder  of 
soft  iron.  In  order  to  restore  the  voice  of  the  telephone,  it  is 
enough  to  approach  the  pole  of  a  permanent  magnet  to  the 
cylinder  of  soft  iron.  It  follows  from  these  experiments  that 
a  Bell  telephone  cannot  act  properly  unless  the  disk  is  subject- 
ed to  an  initial  magnetic  tension  obtained  by  means  of  a  per- 
manent magnet.  It  is  easy  to  deduce  this  assertion  from  a 
consideration  of  the  theory." 

The  assertion  may  be  true  in  the  case  of  Bell  telephones, 
which  are  worked  by  extremely  weak  currents,  but  when  these 
currents  are  relatively  strong,  all  electro-magnets  will  reproduce 
speech  perfectly,  and  we  have  seen  that  M.  Ader  made  a  tele- 
phone with  the  ordinary  electro-magnet  which  acted  perfectly. 

The  action  of  the  currents  sent  through  the  helix  of  a  tele- 
phone can  be  easily  explained.  "Whatever  may  be  the  magnet- 
ic conditions  of  the  bar,  the  induced  currents  of  different  in- 
tensity which  act  upon  it  produce  modifications  in  its  magnetic 
state,  and  hence  the  molecular  vibrations  follow  from  contrac- 
tion and  expansion.  These  vibrations  are  likewise  produced  in 
the  armature  under  the  influence  of  the  magnetizations  and  de- 
magnetizations which  are  produced  by  the  magnetic  action  of 
the  core,  and  they  contribute  to  the  vibrations  of  the  core  it- 
self, while  at  the  same  time  the  modifications  in  the  magnetic 
condition  of  the  system  are  increased  by  the  reaction  of  the 
two  magnetic  parts  upon  each  other. 

When  the  bar  is  made  of  soft  iron,  the  induced  currents  act 
by  creating  magnetizations  of  greater  or  less  energy,  followed  by 
demagnetizations  which  are  the  more  prompt  since  inverse  cur- 
rents always  succeed  to  those  which  have  been  active,  and  this 
causes  the  alternations  of  magnetization  and  demagnetization 
to  be  more  distinct  and  rapid.  When  the  bar  is  magnetized, 


134  THE    TELEPHONE. 

the  action  is  differential,  and  may  be  exerted  in  either  direc- 
tion, according  as  the  induced  currents  corresponding  to  the  vi- 
brations which  are  effected  pass  through  the  receiving  coil  in 
the  same  or  opposite  direction  as  the  magnetic  current  of  the 
bar.  If  these  currents  are  in  the  same  direction,  the  action  is 
strengthening,  and  the  modifications  are  effected  as  if  a  mag- 
netization had  taken  place.  If  these  currents  are  of  opposite 
direction,  the  inverse  effect  is  produced ;  but,  whatever  the  ef- 
fects may  be,  the  molecular  vibrations  maintain  the  same  re- 
ciprocal relations  and  the  same  height  in  the  scale  of  musical 
sounds.  If  the  question  is  considered  from  the  mathematical 
point  of  view,  we  find  the  presence  of  a  constant,  correspond- 
ing with  the  intensity  of  the  current,  which  does  not  exist  in 
mechanical  vibrations,  and  which  may  possibly  be  the  cause  of 
the  peculiar  tone-  of  speech  reproduced  by  the  telephone,  a  tone 
which  has  been  compared  to  the  voice  of  Punch.  M.  Dubois 
Kaymond  has  published  an  interesting  paper  on  this  theory, 
which  appeared  in  Les  Mondes,  February  21st,  1878,  but  we  do 
not  reproduce  it  here,  since  his  remarks  are  too  scientific  for 
the  readers  for  whom  this  work  is  intended.  We  will  only 
add  that  Mr.  C.  W.  Cunningham  asserts  that  the  vibrations 
produced  in  a  telephone  cannot  be  manifested  under  precisely 
the  same  conditions  as  those  which  affect  the  tympanum  of 
the  ear,  because  the  latter  has  a  peculiar  funnel-shaped  form, 
which  excludes  every  fundamental  note,  specially  adapted  to 
it,  and  this  is  not  the  case  with  the  bars  and  magnetic  plates 
which  possess  fundamental  notes  capable  of  greatly  altering 
the  half-tones  of  the  voice.  He  considers  the  alteration  of  the 
voice  observed  in  the  telephone  must  be  ascribed  to  these  fun- 
damental notes. 

M.  Wiesendanger 's  Thermophone.  —  M.  Wiesendanger,  in  an 
article  inserted  in  the  English  Mechanic  and  World  of  Science, 
September  13th,  1878,  ascribes  the  reproduction  of  speech  in 
certain  telephones  to  vibratory  movements  resulting  from  mo- 


135 

lecular  expansions  and  contractions  produced  by  variations  of 
temperature,  and  these  variations  would  follow  from  the  cur- 
rents of  varying  intensity  which  are  transmitted  through  the 
telephonic  circuits.  He  was  conscious  of  one  objection  to  this 
theory,  namely,  that  the  movements  of  expansion  and  contrac- 
tion due  to  heat  are  slowly  produced,  and  consequently  are  not 
capable  of  substantial  action,  rapid  enough  to  produce  vibra- 
tions ;  but  he  considers  that  molecular  effects  need  not  take 
place  under  the  same  conditions  as  those  which  are  displayed 
in  the  case  of  material  substances. 

M.  Wiesendanger  believes  that  this  hypothesis  will  explain 
the  reproduction  of  speech  in  the  receiving  microphones  of. 
Mr.  Hughes,  and  that  it  may  even  be  applied  to  the  theory  of 
the  electro-magnetic  telephone,  if  we  consider  that  a  magnetiz- 
ing helix,  as  well  as  a  magnetic  core,  round  which  an  electric 
current  circulates,  is  more  or  less  heated,  according  to  the  in- 
tensity of  the  current  which  traverses  it,  especially  when  the 
wire  of  the  helix  and  the  core  are  bad  conductors  of  electricity 
and  of  magnetism.  Pursuing  this  idea,  M.  Wiesendanger  has 
sought  to  construct  telephones  in  which  calorific  effects  are 
more  fully  developed,  and  with  this  object  he  used  very  fine 
wire  of  German  silver  and  platinum  to  make  the  coils.  He 
ascertained  that  these  coils  could  produce  sounds  themselves, 
and,  to  increase  their  intensity,  he  put  them  between  disks  of 
iron,  or  on  tin  tubes,  placed  on  resonant  surfaces  close  to  the 
disks.  In  this  way  he  says  that  he  was  able  to  make  a  good 
receiving  telephone  without  employing  magnets.  He  after- 
ward arranged  the  instrument  in  different  ways,  of  which  the 
following  two  are  the  most  noteworthy  : 

In  the  first,  the  electro-magnetic  system  was  simply  formed 
by  a  magnetic  disk  with  a  helix  wound  round  it,  of  which  the 
wire  was  in  connection  with  the  circuit  of  a  microphone,  and 
which  was  fastened  to  the  centre  of  the  parchment  membrane 
of  an  ordinary  string  telephone ;  the  disk  consisted  of  two 


136  THE    TELEPHONE. 

iron  plates  separated  by  a  carbon  disk  of  smaller  diameter,  and 
the  whole  was  so  compressed  as  to  form  a  solid  mass. 

In  the  second,  the  helix  was  wound  on  a  tin  tube,  six  inches 
long  and  five-eighths  of  an  inch  in  diameter,  which  was  solder- 
ed by  merely  a  point  to  the  centre  of  the  diaphragm  of  an  or- 
dinary telephone. 

The  inventor  asserts  that  the  tube  and  diaphragm  only  act 
as  resonators,  and  that  the  sounds  produced  by  this  instrument 
are  nearly  the  same  as  those  obtained  from  the  ordinary  string 
telephone :  the  tunes  of  a  musical  box  were  heard,  and  the  re- 
production of  speech  was  perfect,  both  in  intensity  and  in  dis- 
tinctness of  sound ;  it  even  appeared  that  telephonic  sounds 
were  audible  with  the  tin  tube  alone,  surrounded  by  the  he- 
lix. M.Wiesendanger  says  that  "  these  different  receiving  tele- 
phones show  clearly  that  the  diaphragm  and  magnet  are  not 
essential,  but  merely  accessory,  parts  of  a  telephone." 

VARIOUS  EXPERIMENTS  MADE  WITH  THE  TELEPHONE. 

We  must  now  consider  a  series  of  experiments  which  dem- 
onstrate the  wonderful  properties  of  the  telephone,  and  which 
may  also  give  some  indication  of  the  importance  of  the  influ- 
ences by  which  it  is  liable  to  be  affected. 

Experiments  by  M.  d1  Arsonval. — We  have  seen  that  the  tel- 
ephone is  an  extremely  sensitive  instrument,  but  its  sensitive- 
ness could  scarcely  be  appreciated  by  ordinary  means.  In  or- 
der to  gauge  it,  M.  d'Arsonval  has  compared  it  to  the  nerve  of 
a  frog,  which  has  hitherto  been  regarded  as  the  most  perfect 
of  all  galvanoscopes,  and  it  appears  from  his  experiments  that 
the  sensitiveness  of  the  telephone  is  two  hundred  times  greater 
than  that  of  the  frog's  nerve.  M.  d'Arsonval  has  given  the 
following  account  of  his  researches  in  the  records  of  the  Aca- 
demic des  Sciences,  April  1st,  1878  : 

"  I  prepared  a  frog  in  Galvani's  manner.  I  took  Siemens's 
instrument  of  induction,  used  in  physiology  under  the  name  of 


D'ABSONVAL'S  EXPE  RIME  NTS.  137 

the  chariot  instrument.  I  excited  with  the  ordinary  pincers 
the  sciatic  nerve,  and  I  withdrew  the  induced  coil  until  the 
nerve  no  longer  responded  to  the  electric  excitement.  I  then 
substituted  the  telephone  for  the  nerve,  and  the  induced  cur- 
rent, which  had  ceased  to  excite  the  latter,  made  the  instru- 
ment vibrate  strongly.  I  withdrew  the  induced  coil,  and  the 
telephone  continued  to  vibrate. 

"  In  the  stillness  of  night  I  could  hear  the  vibration  of  the 
telephone  when  the  induced  coil  was  at  a  distance  fifteen  times 
greater  than  the  minimum  at  which  the  excitement  of  the 
nerve  took  place ;  consequently,  if  the  same  law  of  inverse 
squares  applies  to  induction  and  to  distance,  it  is  evident  that 
the  sensitiveness  of  the  telephone  is  two  hundred  times  greater 
than  that  of  the  nerve. 

"The  sensitiveness  of  the  telephone  is  indeed  exquisite. 
We  see  how  much  it  exceeds  that  of  the  galvanoscopic  frog's 
leg,  and  I  have  thought  of  employing  it  as  a  galvanoscope. 
It  is  very  difficult  to  study  the  muscular  and  nervous  currents 
with  a  galvanometer  of  30,000  turns,  because  the  instrument  is 
deficient  in  instantaneous  action,  and  the  needle,  on  account  of 
its  inertia,  cannot  display  the  rapid  succession  of  electric  varia- 
tions, such  as  are  effected,  for  example,  in  a  muscle  thrown  into 
electric  convulsion.  The  telephone  is  free  from  this  incon- 
venience, and  it  responds  by  vibration  to  each  electric  change, 
however  rapid  it  may  be.  The  instrument  is,  therefore,  well 
adapted  for  the  study  of  electric  tetanus  in  the  muscle.  It  is 
certain  that  the  muscular  current  will  excite  the  telephone, 
since  this  current  excites  the  nerve,  which  is  less  sensitive  than 
the  telephone.  But  for  this  purpose  some  special  arrange- 
ment of  the  instrument  is  required. 

"  It  is  true  that  the  telephone  can  only  reveal  the  variations 
of  an  electric  current,  however  faint  they  may  be ;  but  I  have 
been  able,  by  the  use  of  a  very  simple  expedient,  to  reveal  by 
its  means  the  presence  of  a  continuous  current,  also  of  extreme 


138  THE    TELEPHONE. 

faintncss.  I  send  the  current  in  question  into  the  telephone, 
and,  to  obtain  its  variations,  I  break  this  current  mechanically 
with  a  tuning-fork.  If  no  current  is  traversing  the  telephone, 
it  remains  silent.  If,  on  the  other  hand,  the  faintest  current 
exists,  the  telephone  vibrates  in  unison  with  the  tuning-fork." 

Professor  Eick,  of  Wurzburg,  has  also  used  the  telephone  for 
physiological  researches,  but  in  a  direction  precisely  opposite  to 
that  explored  by  M.  d'Arsonval.  He  ascertained  that  when  the 
nerves  of  a  frog  were  placed  in  connection  with  a  telephone, 
they  were  forcibly  contracted  when  any  one  was  speaking  into 
the  instrument,  and  the  force  of  the  contractions  chiefly  de- 
pended on  the  words  pronounced.  For  instance,  the  vowels  a, 
e,  i  produced  hardly  any  effect,  while  o,  and  especially  u,  caused 
a  very  strong  contraction.  The  words  Liege  still,  pronounced 
in  a  loud  voice,  only  produced  a  faint  movement,  while  the 
word  Tucker,  even  when  spoken  in  a  low  voice,  strongly  agi- 
tated the  frog.  These  experiments,  reminding  us  of  those  by 
Galvani,  were  necessarily  based  on  the  effects  produced  by  the 
induced  currents  developed  in  the  telephone,  and  they  show 
that  if  this  instrument  is  a  more  sensitive  galvanoscope  than 
the  nerve  of  a  frog,  the  latter  is  more  susceptible  than  the  most 
perfect  galvanometer. 

Experiments  by  M.  Demoget. — In  order  that  he  might  com- 
pare the  intensity  of  the  sounds  transmitted  by  the  telephone 
with  the  intensity  of  original  sounds,  M.  Demoget  placed  two 
telephones  in  an  open  space.  He  held  the  first  to  his  ear, 
while  his  assistant  withdrew  to  a  distance,  constantly  repeating 
the  same  syllable  with  the  same  intensity  of  tone  in  the  sec- 
ond instrument.  He  first  heard  the  sound  transmitted  by  the 
telephone,  and  then  the  sound  which  reached  him  directly,  so 
that  comparison  was  easy,  and  he  obtained  the  following  results : 

At  a  distance  of  ninety -three  yards  the  original  and  the 
transmitted  sounds  were  received  with  equal  intensity,  while 
the  vibrating  disk  was  about  five  centimetres  from  the  ear. 


DEMOGET'S  EXPERIMENTS.  139 

At  this  moment,  therefore,  the  relative  intensity  was  as  25  to 
81,000,000.  In  other  words,  the  sound  transmitted  by  the 
telephone  was  only  auuuuou  °f  ^e  emitted  sound.  "But," 
said  M.  Demoget,  "  since  the  stations  at  which  we  worked  could 
not  be  regarded  as  two  points  freely  vibrating  in  space,  the 
ratio  may  be  reduced  by  one-half  on  account  of  the  influence 
of  the  earth,  and  the  sound  transmitted  by  the  telephone  may 
be  supposed  to  be  1,500,000  times  weaker  than  that  emitted 
by  the  voice. 

"  Again,  since  we  know  that  the  intensity  of  the  two  sounds 
is  in  proportion  to  the  square  of  the  range  of  vibrations,  it 
may  be  concluded  that  the  vibrations  of  the  two  telephone 
disks  were  in  direct  proportion  to  the  distance,  that  is,  as  5  to 
9000,  or  that  the  vibrations  of  the  sending  telephone  were 
eighteen  hundred  times  greater  than  those  of  the  receiving  tel- 
ephone. These  latter  may,  therefore,  be  compared  to  molecu- 
lar vibrations,  since  the  range  of  those  of  the  sending  telephone 
was  extremely  small. 

"  Without  in  any  degree  detracting  from  the  merit  of  Bell's 
remarkable  invention,"  continues  M.  Demoget, "  it  follows,  from 
what  I  have  said  above,  that  the  telephone,  considered  as  a 
sending  instrument,  leaves  much  to  be  desired,  since  it  only 
transmits  the  -$*$  part  of  the  original  power ;  and  if  it  has 
produced  such  unexpected  results,  this  is  due  to  the  perfection 
of  the  organ  of  hearing,  rather  than  to  the  perfection  of  the 
instrument  itself." 

M.  Demoget  considers  this  loss  of  power  which  takes  place 
in  the  telephone  to  be  chiefly  owing  to  the  eight  transforma- 
tions in  succession  to  which  sound  is  subjected  before  reaching 
the  ear,  setting  aside  the  loss  due  to  the  electric  resistance  of 
the  line,  which  might  in  itself  suffice  to  absorb  the  whole  force. 

In  order  to  estimate  the  force  of  the  induced  currents  which 
act  upon  a  telephone,  M.  Demoget  has  attempted  to  compare 
them  with  currents  of  which  the  intensity  is  known,  and  which 


140  THE   TELEPHONE. 

produce  vibrations  of  like  nature  and  force :  for  tins  purpose 
he  has  made  use  of  two  telephones,  A  and  B,  communicating 
through  a  line  twenty-two  yards  in  lepgth.  He  placed  a  small 
file  in  slight  contact  with  the  vibrating  disk  of  the  telephone 
A,  and  caused  friction  between  the  file  and  a  metallic  plate : 
the  sound  thus  produced  was  necessarily  transmitted  by  the 
telephone  B,  with  an  intensity  which  could  be  estimated.  He 
then  substituted  a  battery  for  the  telephone  A,  and  the  file  was 
introduced  into  the  circuit  by  connecting  it  with  one  of  the 
poles.  The  current  could  only  be  closed  by  the  friction  of  the 
file  with  the  plate,  which  had  a  spring,  and  was  in  communica- 
tion with  the  other  end  of  the  circuit.  In  this  way  broken  cur- 
rents were  obtained,  which  caused  vibration  in  the  telephone  B, 
and  produced  a  sound  of  which  the  intensity  varied  with  the 
strength  of  the  battery  current.  In  this  way  M.  Dcmoget  en- 
deavored to  find  the  electric  intensity  capable  of  producing  a 
sound  similar  to  that  of  the  telephone  A,  and  he  ascertained 
that  it  corresponded  in  intensity  to  that  produced  in  a  small 
thermo-electric  battery  formed  of  an  iron  and  a  copper  wire, 
two  millimetres  in  diameter,  flattened  at  the  end,  and  soldered 
to  the  tin :  the  faint  current  produced  by  this  battery  only 
caused  a  short  wire  galvanometer  to  deviate  two  degrees. 

This  estimate  does  not  appear  to  us  to  unite  so  many  con- 
ditions, of  accuracy  as  to  enable  us  to  deduce  from  it  the  de- 
gree of  sensitiveness  possessed  by  a  telephone — a  sensitiveness 
which  the  experiments  of  Messrs.  Warren  de  la  Rue,  Brongh, 
and  Peirce  show  to  be  much  greater.  Mr.  Warren  de  la  Rue, 
as  we  have  seen,  used  Thomson's  galvanometer,  and  compared 
the  deviation  produced  on  the  scale  of  this  galvanometer  with 
that  caused  by  a  Daniell  cell  traversing  a  circle  completed  by  a 
rheostat :  he  ascertained  that  the  currents  discharged  by  an  or- 
dinary Bell  telephone  are  equivalent  to  those  of  a  Daniell  cell 
traversing  100  megohms  of  resistance — that  is,  6,200,000  miles 
of  telegraphic  wire.  Mr.  Brough,  the  Director  of  Indian  Tele- 


IIELLESEX'S    EXPERIMENTS.  141 

graphs,  considers  that  the  strongest  current  which  at  any  given 
moment  causes  a  Bell  telephone  to  work  does  not  exceed 
loooooo  °f  tne  unit  °f  current,  that  is,  one  Weber,  and  the 
current  transmitted  to  the  stations  on  the  Indian  telegraphic 
line  is  400,000  times  as  strong.  Finally,  Professor  Peirce,  of 
Boston,  compares  the  effects  of  the  telephonic  current  with 
those  which  would  be  produced  by  an  electric  source  of  which 
the  electro -motive  force  should  be  •?  0  ^  0  0  part  of  a  volt,  or 
one  Daniell  cell.  Mr.  Peirce  justly  remarks  that  it  is  difficult 
to  estimate  the  real  value  of  these  kinds  of  currents  at  any  pre- 
cise sum,  since  it  essentially  varies  according  to  the  intensity 
of  the  sounds  produced  on  the  transmitting  telephone;  but  it 
may  be  affirmed  that  it  is  less  than  the  -nro"o-o<ro-  Part  °f  tue 
current  usually  employed  to  work  the  instruments  on  tele- 
graphic lines. 

Signer  Galileo  Ferraris,  who  has  recently  published  an  inter- 
esting treatise  on  this  question  in  the  Atti  della  Reale  Acade- 
mia  delle  Scienze  di  Torino  (June  13th,  18Y8),  states  that  the  in- 
tensity of  the  currents  produced  by  the  ordinary  Bell  telephone 
varies  with  the  pitch  of  the  sound  emitted. 

Experiments  by  M.  Hellesen,  of  Copenhagen.  —  In  order  to 
estimate  the  reciprocal  effects  of  different  parts  of  a  telephone, 
M.  Hellesen  has  made  telephones  of  the  same  size  with  three 
different  arrangements  which  act  inversely  to  each  other.  The 
first  was  of  the  ordinary  form ;  the  second  like  that  of  Bell's 
first  system,  that  is,  with  a  membrane  supporting  a  small  iron 
armature  on  its  centre,  instead  of  a  vibrating  disk;  and  the 
third  telephone  consisted  of  a  hollow  cylindrical  magnet,  with 
the  vibrating  disk  fixed  to  one  of  its  poles,  and  the  disk  was 
adapted  to  move  before  a  flat,  snail-shaped  spiral,  of  which  the 
number  of  spirals  equalled  those  of  the  two  other  helices.  In 
this  last  arrangement,  the  induced  currents  resulting  from  the 
vibrations  of  the  voice  might  be  assimilated  to  those  which  fol- 
low from  the  approximation  and  withdrawal  of  the  two  parallel 


142  THE    TELEPHONE. 

spirals,  one  of  which  should  be  traversed  by  a  current.  It  is 
this  last  arrangement  which  Mr.  Bell  has  adopted  as  produ- 
cing the  best  effects  and,  it  is  rare  in  the  history  of  discover- 
ies that  an  inventor  hits  at  once  on  the  best  arrangement  of  his 
instrument. 

Experiments  by  M.  Zetsche. — There  are  always  a  few  per- 
verse minds,  impelled  by  a  spirit  of  contradiction  to  deny  evi- 
dence, and  thus  they  attempt  to  depreciate  a  discovery  of  which 
the  glory  irritates  them.  The  telephone  and  the  phonograph 
have  been  the  objects  of  such  unworthy  criticism.  It  has  been 
said  that  electric  action  had  nothing  to  do  with  the  effects  pro- 
duced in  the  telephone,  and  that  it  only  acted  under  the  influ- 
ence of  mechanical  vibrations  transmitted  by  the  conducting 
wire,  just  as  in  a  string  telephone.  It  was  in  vain  to  demon- 
strate to  these  obstinate  minds  that  no  sound  is  produced  when 
the  circuit  is  broken,  and  in  order  to  convince  them  M.  Zetsche 
has  made  some  experiments  to  show,  from  the  mode  in  which 
sound  is  propagated,  that  it  is  absurd  to  ascribe  the  sound  pro- 
duced in  a  telephone  to  mechanical  vibration.  He  wrote  to 
this  effect  in  an  article  inserted  in  the  Journal  Telegraphique, 
Berne,  January  25th,  1878  : 

"The  correspondence  by  telephone  between  Leipzig  and 
Dresden  affords  another  proof  that  the  sounds  which  reproduce 
words  at  the  receiving-station  are  due  to  electric  currents,  and 
not  to  mechanical  vibrations.  The  velocity  with  which  sound 
is  transmitted  by  vibrations  on  the  wire,  in  the  case  of  longitu- 
dinal undulations,  may  be  estimated  at  three  miles  one  furlong 
a  second,  so  that  the  sound  ought  to  traverse  the  distance  from 
Leipzig  to  Dresden  in  twenty -five  seconds.  The  same  time 
ought  to  elapse  before  receiving  the  answer;  consequently, 
there  should  be  an  interval  of  more  than  three-quarters  of  a 
minute  allowed  for  each  exchange  of  communication,  which  is 
by  no  means  the  case." 

Experiments  which  may  be  made  by  any  one, — We  will  con- 


THE    MICKOPI10XE.  143 

elude  tLis  chapter,  devoted  to  the  account  of  the  different  ex- 
periments made  with  the  telephone,  by  the  mention  of  a  singu- 
lar experiment,  which,  although  easily  performed,  has  only  been 
suggested  a  few  months  ago  by  a  Pennsylvania  newspaper.  It 
consists  in  the  transmission  of  speech  by  a  telephone  simply 
laid  on  some  part  of  the  human  body  adjacent  to  the  chest. 
It  has  been  asserted  that  any  part  of  the  body  will  produce 
this  effect,  but  according  to  my  experience,  I  could  only  suc- 
ceed when  the  telephone  was  firmly  applied  to  my  chest.  Un- 
der such  conditions,  and  even  through  my  clothes,  I  could  make 
myself  heard  when  speaking  in  a  very  loud  voice,  from  which 
it  appears  that  the  whole  of  the  human  body  takes  part  in  the 
vibrations  produced  by  the  voice.  In  this  case  the  vibrations 
are  mechanically  transmitted  to  the"  diaphragm  of  the  sending 
telephone — not  by  the  air,  but  by  the  body  itself,  acting  on  the 
outside  of  the  telephone. 

THE  MICROPHOXE. 

The  microphone  is,  in  fact,  only  the  sender  of  a  battery  tele- 
phone, but  with  such  distinctive  characteristics  that  it  may  be 
regarded  as  an  original  invention  which  is  entitled  to  a  special 
name.  The  invention  has  lately  given  rise  to  an  unfortunate 
controversy  between  its  inventor,  Mr.  Hughes,  and  Mr.  Edison, 
the  inventor  of  the  carbon  telephone  and  the  phonograph — a 
controversy  which  has  been  embittered  by  the  newspapers,  and 
for  which  there  were  no  grounds ;  for,  although  the  scientific 
principle  of  the  microphone  may  appear  to  be  the  same  as  that 
of  Mr.  Edison's  carbon  sender,  its  arrangement  is  totally  differ- 
ent; its  mode  of  action  is  not  the  same,  and  the  effect  required 
of  it  is  of  quite  another  kind.  Less  than  this  is  needed  to 
constitute  a  new  invention.  Besides,  a  thorough  examination 
of  the  very  principle  of  the  instrument  must  make  us  wonder 
at  Mr.  Edison's  claim  to  priority.  He  cannot,  in  fact,  regard  as 
his  exclusive  possession  the  discovery  of  the  property  possessed 


144  THE    TELEPHONE. 

by  some  substances  of  moderate  conductivity  of  having  tins 
power  modified  by  pressure.  In  1856,  and  often  subsequent- 
ly—as, for  example,  in  1864,  1872,  1874,  and  1875—1  made 
numerous  experiments  on  this  point,  which  are  described  in  the 
first  volume  of  the  second  edition  of  my  "Expose  des  Appli- 
cations de  FElectricite,"  and  also  in  several  papers  presented 
to  the  Academic  des  Sciences,  and  inserted  in  their  comptes 
rendus.  M.  Clarac  again,  in  1865,  employed  a  tube  made  of 
plumbago,  and  provided  with  a  movable  electrode,  to  produce 
variable  resistances  in  a  telegraphic  circuit.  Besides,  in  Mr. 
Edison's  telephonic  sender,  the  carbon  disk,  as  we  have  seen, 
must  be  subjected  to  a  certain  initial  pressure,  in  order  that 
the  current  may  not  be  broken  by  the  vibrations  of  the  plate 
on  which  it  rests,  and  consequently  the  modifications  of  resist- 
ance in  the  circuit  which  produce  articulate  sounds  are  only 
caused  by  greater  or  less  increase  and  diminution  of  pressure, 
that  is,  by  differential  actions.  "We  shall  presently  see  that 
this  is  not  the  case  with  the  microphone.  In  the  first  place, 
the  carbon  contact  is  effected  in  the  latter  instrument  on  oth- 
er carbons  and  not  with  platinum  disks,  and  these  contacts  are 
multiple.  In  the  second  place,  the  pressure  exerted  on  all  the 
points  of  contact  is  excessively  slight,  so  that  the  resistances 
can  be  varied  in  an  infinitely  greater  ratio  than  in  Mr.  Edison's 
system ;  and  for  this  very  reason  it  is  possible  to  magnify  the 
sounds.  In  the  third  place,  a  microphone  can  be  made  of 
other  substances  besides  carbon.  Finally,  no  vibrating  disk  is 
needed  to  make  the  microphone  act;  the  simple  medium  of 
air  is  enough,  so  that  it  is  possible  to  work  the  instrument 
from  some  little  distance. 

We  do  not,  therefore,  see  the  grounds  for  Mr.  Edison's  as- 
sertions, and  especially  for  the  way  in  which  he  has  spoken  of 
Messrs.  Hughes  and  Preece,  who  are  well  known  in  science, 
and  are  in  all  respects  honorable  men.  I  repeat  my  regret 
that  Mr.  Edison  should  have  made  this  ill-judged  attack  on 


145 

them,  since  it  must  injure  himself,  and  is  unworthy  of  an  in- 
ventor of  such  distinction.  If  we  look  at  the  question  from 
another  point  of  view,  we  must  ask  Mr.  Edison  why,  if  he  in- 
vented the  microphone,  he  did  not  make  us  acquainted  with 
its  properties  and  results.  These  results  are  indeed  startling, 
since  the  microphone  has  in  so  short  a  time  attracted  general 
attention;  and  it  is  evident  that  the  clear-sighted  genius  of 
this  celebrated  American  inventor  would  have  made  the  most 
of  the  discovery  if  it  were  really  his.  The  only  justification 
for  Mr.  Edison's  claim  consists  in  his  ignorance  of  the  purely 
scientific  discoveries  made  in  Europe,  so  that  he  supposed  the 
invention  of  the  microphone  to  be  wholly  involved  in  the 
principle  which  he  regards  as  his  peculiar  discovery. 

In  Mr.  Hughes's  instrument,  which  we  are  now  considering, 
the  sounds,  instead  of  reaching  the  receiving-stations  much  di- 
minished, which  is  the  case  with  ordinary  telephones,  and  even 
with  that  of  Mr.  Edison,  are  often  remarkably  increased,  and  it 
is  for  this  reason  that  Mr.  Hughes  has  given  to  this  telephonic 
system  the  name  of  microphone,  since  it  can  be  employed  to 
discover  very  faint  sounds.  Yet  we  must  add  that  this  in- 
crease really  takes  place  only  when  the  sounds  result  from  me- 
chanical vibrations  transmitted  by  solid  substances  to  the  send- 
ing instrument.  The  sounds  propagated  through  the  air  are 
undoubtedly  a  little  more  intense  than  in  the  ordinary  system, 
but  they  lose  some  of  their  force,  and  therefore  it  cannot  be 
said  that  in  this  case  the  microphone  has  the  same  effect  upon 
sounds  as  the  microscope  has  on  objects  on  which  light  is 
thrown.  It  is  true  that  with  this  system  it  is  possible  to 
speak  at  a  distance  from  the  instrument,  and  I  have  even  been 
able  to  transmit  conversation  in  a  loud  voice,  when  standing  at 
a  distance  of  nine  yards  from  the  microphone.  When  close 
to  the  instrument,  I  was  also  perfectly  able  to  make  myself 
heard  at  the  receiving-station  while  speaking  in  a  low  voice, 
and  even  to  send  the  sounds  to  a  distance  of  ten  or  fifteen  cen- 

7 


146  THE   TELEPHONE. 

timetres  from  the  mouth-piece  of  the  receiving  telephone  by 
raising  the  voice  a  little ;  but  the  increase  of  sound  is  not  real- 
ly very  evident  unless  it  is  produced  by  a  mechanical  action 
transmitted  to  the  standard  of  the  instrument. 

Thus  the  steps  of  a  fly  walking  on  the  stand  are  clearly 
heard,  and  give  the  sensation  of  a  horse's  tread;  and  even  a 
fly's  scream,  especially  at  the  moment  of  death,  is  said  by  Mr. 
Hughes  to  be  audible.  The  rustling  of  a  feather  or  of  a  piece 
of  stuff  on  the  board  of  the  instrument,  sounds  completely  in- 
audible in  ordinary  circumstances,  are  distinctly  heard  in  the 
microphone.  It  is  the  same  with  the  ticking  of  a  watch 
placed  upon  the  stand,  which  may  be  heard  at  ten  or  fifteen 
centimetres  from  the  receiver.  A  small  musical  box  placed 
upon  the  instrument  gives  out  so  much  sound,  in  consequence 
of  its  vibratory  movements,  that  it  is  impossible  to  distinguish 
the  notes,  and  in  order  to  do  so  it  is  necessary  to  place  the 
box  close  to  the  instrument,  without  allowing  it  to  come  in 
contact  with  any  of  its  constituent  parts.  It  therefore  ap- 
pears that  the  instrument  is  affected  by  the  vibrations  of  air, 
and  the  transmitted  sounds  are  fainter  than  those  heard  close 
to  the  box.  On  the  other  hand,  the  vibrations  produced  by 
the  pendulum  of  a  clock,  when  placed  in  communication  with 
the  standard  of  the  instrument  by  means  of  a  metallic  rod,  are 
heard  perfectly,  and  may  even  be  distinguished  when  the  con- 
nection is  made  by  the  intervention  of  a  copper  wire.  A  cur- 
rent of  air  projected  on  the  system  gives  the  sensation  of  a 
trickle  of  water  heard  in  the  distance.  Finally,  the  rumbling 
of  a  carriage  outside  the  house  is  transformed  into  a  very  in- 
tense crackling  noise,  which  may  combine  with  the  ticking  of 
a  watch,  and  will  often  overpower  it. 

Different  Systems  of  Microphones. — The  microphone  has 
been  made  in  several  ways,  but  the  one  represented  in  Fig.  39 
is  the  arrangement  which  renders  it  the  most  sensitive.  In 
this  system,  two  small  carbon  cubes,  A,  B,  are  placed  one  above 


DIFFERENT   SYSTEMS.  147 

the  other  on  a  vertical  wooden  prism ;  two  holes  are  pierced 
in  the  cubes  to  serve  as  sockets  for  a  spindle-shaped  carbon 
pencil,  that  is,  with  the  points  fined  off  at  the  two  ends,  and 


FIG.  39. 

about  four  centimetres  long:  if  of  a  large  size,  the  inertia  will 
be  too  great.  One  end  of  this  pencil  is  in  the  cavity  of  the 
lower  carbon,  and  the  other  must  move  freely  in  the  upper 
cavity  which  maintains  it  in  a  position  approaching  to  that  of 
instable  equilibrium,  that  is,  in  a  vertical  position.  Mr.  Hughes 
states  that  the  carbons  become  more  effective  if  they  are  steeped 
in  a  bath  of  mercury  at  red  heat,  but  they  will  act  well  without 
undergoing  this  process.  The  two  carbon  cubes  are  also  pro- 
vided with  metallic  contacts  which  admit  of  their  being  placed 
in  connection  with  the  circuit  of  an  ordinary  telephone  in  which 
a  Leclanche  battery  has  been  placed,  or  one,  two,  or  three  Daniell 
cells,  with  an  additional  resistance  introduced  into  the  circuit. 


148  THE   TELEPHONE. 

In  order  to  use  this  instrument,  it  is  placed  on  a  table,  with 
the  board  which  serves  to  support  it,  taking  care  to  deaden  any 
extraneous  vibrations  by  interposing  between  this  board  and 
the  table  several  folds  of  stuff  so  arranged  as  to  form  a  cushion, 
or,  which  is  better,  a  belt  of  wadding,  or  two  caoutchouc  tubes : 
what  is  said  by  a  person  standing  before  this  system  is  immedi- 
ately reproduced  in  the  telephone,  and  if  a  watch  is  placed  on 
the  stand,  or  a  box  with  a  fly  enclosed  in  it,  all  its  movements 
are  heard.  The  instrument  is  so  sensitive  that  words  said  in  a 
low  voice  are  most  easily  heard,  and  it  is  possible,  as  I  have  al- 
ready said,  to  hear  the  speaker  when  he  is  standing  nine  yards 
from  the  microphone.  Yet  some  precautions  are  necessary  in 
order  to  obtain  good  results  with  this  system,  and  besides  the 
cushions  placed  beneath  the  instrument  to  guard  it  from  the 
extraneous  vibrations  which  might  ensue  from  any  movements 
communicated  to  tie  table,  it  is  also  necessary  to  regulate  the 
position  of  the  carbon  pencil.  It  must  always  rest  on  some 
point  of  the  rim  of  the  upper  cavity ;  but  as  the  contact  may 
be  more  or  less  satisfactory,  experience  alone  will  show  when  it 
is  in  the  best  position,  and  it  is  a  good  plan  to  make  use  of  a 
watch  to  ascertain  this.  The  ear  is  then  applied  to  the  tele- 
phone, and  the  pencil  is  placed  in  different  positions  until  the 
maximum  effect  is  obtained.  To  avoid  the  necessity  of  regu- 
lating the  instrument  in  this  way,  which  must  be  done  repeat- 
edly by  this  arrangement,  MM.  Chardin  and  Berjot,  who  are 
ingenious  in  the  construction  of  telephones  on  this  pattern, 
have  added  to  it  a  small  spring-plate,  of  which  the  pressure  can 
be  regulated,  and  which  rests  against  the  carbon  pencil  itself. 
This  system  works  well. 

M.  Gaiffe,  by  constructing  it  like  a  scientific  instrument,  has 
given  the  instrument  a  more  elegant  form.  Fig.  40  represents 
one  of  his  two  models.  In  this  case,  the  cubes  or  carbon  dice 
are  supported  by  metallic  holders,  and  the  upper  one,.E,  is  made 
to  move  up  and  down  a  copper  column,  G,  so  as  to  be  placed 


CABETTE    SYSTEM. 


149 


in  the  right  position  by  tightening  the  screw,  V.  In  this  way 
the  carbon  pencil  can  be  made  to  incline  more  or  less,  and  its 
pressure  on  the  upper  carbon  can  be  altered  at  pleasure.  When 


Fio.  40. 

the  pencil  is  in  a  vertical  position,  the  instrument  transmits 
articulate  sounds  with  difficulty,  on  account  of  the  instability 
of  the  points  of  contact,  and  rustling  sounds  are  heard.  When 
the  inclination  of  the  pencil  is  too  great,  the  sounds  are  purer 
and  more  distinct,  but  the  instrument  is  less  sensitive.  The 
exact  degree  of  inclination  should  be  ascertained,  which  is  easily 
done  by  experiment.  In  another  model  M.  Gaiffe  substitutes 
for  the  carbon  pencil  a  very  thin  square  plate  of  the  same  ma- 
terial, bevelled  on  its  lower  and  upper  surfaces,  and  revolving 
in  a  groove  cut  in  the  lower  carbon.  This  plate  must  be  only 
slightly  inclined  in  order  to  touch  the  upper  carbon,  and  under 
these  conditions  it  transmits  speech  more  loudly  and  distinctly. 
I  must  also  mention  another  arrangement,  devised  by  Cap- 
tain Carette,  of  the  French  Engineers,  which  is  very  successful 
in  transmitting  inarticulate  sounds.  In  this  case  the  vertical 
carbon-  is  pear-shaped,  and  its  larger  end  rests  in  a  hole  made 


150 


THE   TELEPHONE. 


in  the  lower  carbon ;  its  upper  and  pointed  end  goes  into  a 
small  hole  made  in  the  upper  carbon,  but  so  as  hardly  to  touch 
it,  and  there  is  a  screw  to  regulate  the  distance  between  the 
two  carbons.  Under  such  conditions,  the  contacts  are  so  un- 
stable that  almost  anything  will  put  an  end  to  them,  and  con- 
sequently the  variations  in  the  intensity  of  the  transmitted 
current  are  so  strong  that  the  sounds  produced  by  the  tele- 
phone may  be  heard  at  the  distance  of  several  yards. 

Fig.  41  represents  another  arrangement,  devised  by  M.  Du- 
cretet.  The  two  carbon  blocks  are  at  D  D',  the  movable  carbon 
pencil  is  at  C,  the  telephone  at  T,  and  the  binding  screws  at 
B  B'.  An  enlarged  figure  of  the  arrangement  of  the  carbons 
is  given  on  the  left.  The  arm  which  holds  the  upper  carbon, 
D,  is  fastened  to  a  rod,  bearing  a  plate,  P',  of  which  the  sur- 


FIG.  41. 


face  is  rough,  and  a  little  cage,  C',  made  of  wire  netting,  can 
be  placed  upon  the  plate,  so  as  to  enable  us  to  study  the  move- 


ments of  living  insects. 


151 

When  speech  is  to  be  transmitted  with  a  force  which  can 
make  the  telephone  audible  in  a  large  room,  the  microphone 
must  have  a  special  arrangement,  and  Fig.  42  represents  the 
one  which  Mr.  Hughes  considers  the  most  successful,  to  which 
he  has  given  the  name  of  speaker. 

In  this  new  form,  the  movable  carbon  which  is  required  to 
produce  the  variable  contacts  is  at  C,  at  the  end  of  a  horizon- 


Fio.  42. 


tal  bar,  B  A,  properly  balanced  so  as  to  move  up  and  down  on 
its  central  point.  The  support  on  which  the  bar  oscillates  is 
fastened  to  the  end  of  a  spring -plate  in  order  that  it  may 
vibrate  more  easily,  and  the  lower  carbon  is  placed  at  D,  below 
the  first.  It  consists  of  two  pieces  laid  upon  each  other,  so  as 
to  increase  the  sensitiveness  of  the  instrument,  and  we  repre- 
sent the  upper  piece  at  E,  which  is  raised,  so  as  to  show  that 
when  it  is  desired  only  one  of  these  carbons  need  be  used. 
For  this  purpose  the  carbon,  E.  is  fastened  to  a  morsel  of  paper, 
which  is  fixed  to  the  little  board,  and  contributes  to  the  articu- 
lation. A  spring,  R,  of  which  the  tension  can  be  regulated  by 
the  screw  £,*  serves  to  regulate  the  pressure  of  the  two  carbons. 
Mr.  Hughes  recommends  the  use  of  metallized  charcoal  pre- 
pared from  deal.1  The  whole  is  then  enclosed  in  a  semi- 

1  These  carbons  are  made  by  heating,  in  a  temperature  gradually  raised 


152  THE   TELEPHONE. 

cylindrical  case,  H I G,  made  of  very  thin  pieces  of  deal,  and 
the  system  is  fixed,  together  with  another  similar  system,  in  a 
flat  box,  M  J  L  I,  which,  on  the  side  M  I,  presents  an  opening 
before  which  the  speaker  stands,  taking  care  to  keep  his  lower 
lip  at  a  distance  of  two  centimetres  from  the  bottom  of  the 
box.  If  the  two  telephones  are  connected  for  strength,  and  if 
the  battery  employed  consists  of  two  cells  of  bichromate  of 
potash,  it  is  possible  to  act  so  strongly  on  the  current,  that, 
after  traversing  an  induction  coil  only  six  centimetres  long,  a 
telephone  of  Bell's  square  model  can  be  made  to  speak,  so  as 
to  be  heard  from  all  parts  of  a  room ;  a  speaking-tube,  about 
a  yard  long,  must  indeed  be  applied  to  it.  Mr.  Hughes  asserts 
that  the  sounds  produced  by  it  are  nearly  as  loud  as  those  of 
the  phonograph,  and  this  is  confirmed  by  Mr.  Thomson. 

M.  Boudet  de  Paris  has  lately  invented  a  microphone  speak- 
er of  the  same  kind,  with  which  it  is  possible  to  make  a  small 
telephone  utter  a  loud  sound.  An  induction  coil,  influenced 
by  a  single  Leclanche  cell,  must  be  employed. 

Suppose  that  a  very  small  carbon  rod  with  pointed  ends  is 
placed  at  the  bottom  of  a  box,  of  about  the  size  of  a  watch. 
One  end  of  the  rod  rests  against  a  morsel  of  carbon,  which  is 
fastened  to  a  very  thin  steel  diaphragm,  placed  before  a  mouth- 
piece which  acts  as  a  lid  to  the  box,  and  is  screwed  above  it. 
Next,  suppose  that  a  small  piece  of  paper,  folded  in  two,  in  the 
shape  of  the  letter  V,  is  fixed  above  that  part  of  the  carbon  in 
contact  with  the  carbon  of  the  diaphragm.  This  constitutes 
the  instrument,  and  in  order  to  work  it,  it  must  be  held  in  a 
vertical  position  before  the  mouth,  at  a  distance  of  about  three 
centimetres,  and  it  is  necessary  to  speak  in  the  ordinary  tone. 
If  the  telephone  is  placed  in  direct  communication  with  this 
instrument,  it  will  send  the  voice  to  a  distance.  Without  em- 


to  white  heat,  fragments  of  deal  of  a  close  fibre,  which  is  enclosed  in  an 
iron  tube  or  box  hermetically  sealed. 


BOUDET'S  SPEAKER.  153 

ploying  a  Leclanche  cell,  the  voice  may  be  heard  at  the  dis- 
tance of  ten  yards,  if  one  of  the  carbons  used  for  the  phono- 
graph is  placed  before  the  mouth-piece  of  the  telephone. 

In  this  system,  the  sensitiveness  of  the  instrument  is  entirely 
due  to  the  slightness  of  the  contact  between  the  two  carbons, 
and  the  slight  elasticity  of  the  folded  paper  constitutes  the 
contact.  Perhaps  the  paper  itself  has  some  influence ;  at  any 
rate  the  most  delicate  spiral  spring  is  incapable  of  producing 
the  same  effect,  and  it  is  necessary  to  suspend  the  instrument 
vertically,  in  order  that  the  weight  of  the  movable  carbon  may 
not  affect  it.  It  can  be  regulated  by  depressing  or  elevating 
that  part  of  the  paper  which  rests  on  the  carbon  rod. 

Although  it  is  possible  to  work  all  telephones  with  this  in- 
strument, some  are  more  effective  than  others.  The  mouth- 
piece must  be  concave,  and  the  diaphragm  must  be  close  to  its 
rira,  and  must  be  made  of  a  particular  kind  of  tin.  The  or 
dinary  diaphragm  does  not  act  well,  and  M.  Boudet  de  Paris 
has  tried  several,  so  as  to  obtain  the  maximum  effect. 

It  is  certain  that  when  the  instruments  are  as  well  regulated 
as  those  which  the  inventor  has  deposited  with  me,  their  re- 
sults are  really  surprising.  It  is  even  possible,  by  using  several 
microphones  at  the  sending  station,  to  obtain  the  reproduction 
of  duets,  and  even  of  trios,  with  remarkable  effect. 

With  this  kind  of  microphone  speaker  M.  Boudet  de  Paris 
is  able  to  transmit  speech  into  a  snuffbox  telephone,  merely 
consisting  of  a  flat  helix  of  wire,  placed  before  a  slightly  mag- 
netized steel  plate,  and  without  insertion  of  a  magnetic  core. 
A  single  Leclanche  cell  was  enough.  An  experiment  of  the 
same  nature  was  tried  in  England,  but  it  was  found  necessary 
to  use  six  Leclanche  cells. 

The  microphone  may  also  be  made  of  morsels  of  carbon 
pressed  into  a  box  between  two  metallic  electrodes,  or  enclosed 
in  a  tube  with  two  electrodes  represented  by  two  elongated 
fragments  of  carbon.  In  the  latter  case  the  carbons  ought  to 

7* 


154 


THE    TELEPHONE. 


be  as  cylindrical  as  possible,  and  those  made  by  .M.  Carre  for 
the  Jablochkoff  candles  are  very  suitable.  Fig.  43  represents 
an  instrument  of  this  kind  which  M.  Gaiffe  arranged  for  me, 
and  which,  as  we  shall  see,  serves  as  a  thermoscope  (Fig.  44). 


FIGS.  43,  44. 

It  is  composed  of  a  quill  filled  with  morsels  of  carbon,  and 
those  at  the  two  ends  are  tipped  with  metal.  One  of  these 
metal  tips  ends  in  a  large-headed  screw  which,  by  means  of  its 
supports  A  B,  is  able  to  press  more  or  less  on  the  morsels  of 
carbon  in  the  tube,  and  consequently  to  establish  a  more  or 
less  intimate  contact  between  them.  When  the  instrument 
is  properly  regulated,  speech  can  be  reproduced  by  speaking 
above  the  tube.  It  is  therefore  a  microphone  as  well  as  a 
thermoscope.  Mr.  Hughes  has  remarked  one  curious  fact, 
namely,  that  if  the  different  letters  of  the  alphabet  are  pro- 
nounced separately  before  this  sort  of  microphone,  some  of 
them  are  much  more  distinctly  heard  than  others,  and  it  is  pre- 
cisely those  which  correspond  to  the  breathings  of  the  voice. 
A  microphone  of  this  kind  may  be  made  by  substituting  for 


155 

the  carbon  powders  of  more  or  less  conductivity,  or  even  metal 
filings.  I  have  shown  in  my  paper  on  the  action  of  substances 
of  moderate  conductivity,  that  such  power  varies  considerably 
with  the  pressure  and  the  temperature ;  and  as  the  microphone 
is  based  on  the  differences  of  conducting  power  which  result 
from  differences  of  pressure,  we  can  understand  that  these  pow- 
ders may  be  used  as  a  means  of  telephonic  transmission.  In 
a  recent  arrangement  of  this  system  Mr.  Hughes  has  made  the 
powder  adhere  together  with  a  sort  of  gum,  and  has  thus  made 
a  cylindrical  pencil  which,  when  connected  with  two  electrodes 
which  are  good  conductors,  can  produce  effects  analogous  to 
those  we  have  just  described.  As  I  have  said,  it  is  possible  to 
use  metal  filings,  but  Mr.  Hughes  prefers  powdered  charcoal. 

Mr.  Blyth  states  that  a  flat  box,*about  15 -inches  by  9,  filled 
with  coke,  and  with  two  tin  electrodes  fixed  to  the  two  ends,  is 
one  of  the  best  arrangements  for  a  microphone.  He  says  that 
three  of  these  instruments,  hung  like  pictures  against  the  wall 
of  a  room,  would  suffice,  when  influenced  by  a  single  Leclanche 
cell,  to  make  all  the  sounds  produced  in  a  telephone  audible, 
and  especially  vocal  airs.  Mr.  Blyth  even  asserts  that  a  micro- 
phone capable  of  transmitting  speech  can  be  made  with  a  sim- 
ple piece  of  coke,  connected  with  the  circuit  by  its  two  ends, 
but  it  must  be  coke  :  a  retort  carbon,  with  electrodes,  will 
not  act. 

It  is  a  remarkable  property  of  these  kinds  of  microphones 
that  they  can  act  without  a  battery,  at  least  when  they  are  so 
arranged  as  to  form  a  voltaic  element  for  themselves,  and  this 
can  be  done  by  throwing  water  on  the  carbons.  Mr.  Blyth, 
who  was  the  first  to  speak  of  this  system,  does  not  distinctly 
indicate  its  arrangement,  and  we  may  assume  that  his  instru- 
ment did  not  differ  from  the  one  we  have  already  described,  to 
which  water  must  have  been  added.  In  this  way,  indeed,  I 
have  been  able  to  transmit  not  only  the  ticking  of  a  watch  and 
the  sounds  of  a  musical  box,  Tbut  speech  itself,  which  was  often 


156  THE    TELEPHONE. 

more  distinctly  expressed  than  in  an  ordinary  microphone,  since 
it  was  free  from  the  sputtering  sound  which  is  apt  to  accom- 
pany the  latter.  Mr.  Blyth  also  asserts  that  sounds  may  be 
transmitted  without -the  addition  of  water,  but  in  this  case  he 
considers  that  the  result  is  due  to  the  moisture  of  the  breath. 
Certainly  much  moisture  is  not  required  to  set  a  voltaic  couple 
in  action,  especially  when  a  telephone  is  the  instrument  of  man- 
ifestation. The  ordinary  microphone  may  be  used  without  a 
battery,  if  the  circuit  in  which  it  is  inserted  is  in  communica- 
tion with  the  earth  by  means  of  earthen  cakes ;  the  currents 
which  then  traverse  the  circuit  will  suffice  to  make  the  tickings 
of  a  watch  placed  upon  the  microphone  perfectly  audible.  M. 
Cauderay,  of  Lausanne,  in  a  paper  sent  to  the  Academic  des  Sci- 
ences, July  8,  1878,  informs  us  that  he  made  this  experiment 
on  a  telegraphic  wire  which  unites  the  Hotel  des  Alpes  at  Mon- 
treux  with  a  chalet  on  the  hill — a  distance  of  about  550  yards. 
The  Microphone  used  as  a  Speaking  Instrument. — The  mi- 
crophone cannot  only  transmit  speech,  but  it  can  also,  under 
certain  conditions,  reproduce  it,  and  consequently  supply  the 
place  of  the  receiving  telephone.  This  seems  difficult  to  un- 
derstand, since  a  cause  for  the  vibratory  motion  produced  in 
part  of  the  circuit  itself  can  only  be  sought  in  the  variations  in 
intensity  of  the  current,  and  the  effects  of  attraction  and  mag- 
netization have  nothing  to  do  with  it.  Can  the  action  be  re- 
ferred to  the  repulsions  reciprocally  exerted  by  the  contiguous 
elements  of  the  same  current  1  Or  are  we  to  consider  it  to  be 
of  the  same  nature  as  that  which  causes  the  emission  of  sounds 
from  a  wire  when  a  broken  current  passes  through  it,  so  that 
an  electric  current  is  itself  a  vibratory  current,  as  Mr.  Hughes 
believes?  It  is  difficult  to  reply  to  these  questions  in  the 
present  state  of  science ;  we  can  only  state  the  fact,  which  has 
been  published  by  Messrs.  Hughes,  Blyth,  Robert  Courtenay, 
and  even  by  Mr.  Edison  himself.  I  have  been  able  to  verify 
the  fact  myself  under  the  experimental  conditions  indicated  by 


CAPABILITIES    OF   THE    MICROPHONE.  157 

Mr.  Hughes,  but  I  was  not  so  successful  in  the  attempt  to  repeat 
Mr.  Blyth's  experiments.  This  gentleman  stated  that  in  order 
to  hear  speech  in  a  microphone  it  would  be  enough  to  use  the 
model  made  from  fragments  of  carbon,  as  we  have  described, 
to  join  to  it  a  second  microphone  of  the  same  kind,  and  to  in- 
troduce into  the  circuit  a  battery  consisting  of  two  Grove  ele- 
ments. If  any  one  then  speaks  above  the  carbons  of  one  of 
the  microphones,  what  is  said  should  be  distinctly  heard  by  the 
person  who  puts  his  ear  to  the  other,  and  the  importance  of 
the  sounds  thus  produced  will  correspond  with  the  intensity  of 
the  electric  source  employed.  As  I  have  said,  I  was  unable  by 
following  this  method  to  hear  any  sound,  still  less  articulate 
speech ;  and  if  other  experiments  had  not  convinced  me,  I 
should  have  doubted  the  correctness  of  the-  statement.  But 
this  negative  experiment  does  not,  in  fact,  prove  anything,  since 
it  is  possible  that  my  conditions  were  wrong,  and  that  the  cin- 
ders which  I  employed  were  not  subject  to  the  same  conditions 
as  Mr.  Blyth's  fragments  of  coke. 

With  respect  to  Mr.  Hughes' s  experiments,  I  have  repeated 
them  with  the  microphone  made  by  M  M.  Chardin  and  Berjot, 
using  that  by  M.  Gaiffe  as  the  sender,  and  I  ascertained  that 
with  a  battery  of  only  four  Leclanche  cells,  a  scratch  made  on 
the  sender,  and  even  the  tremulous  motion  and  the  airs  played 
in  a  little  musical  box  placed  on  the  sender,  were  reproduced — 
very  faintly,  it  is  true — in  the  second  microphone  ;  in  order  to 
perceive  them,  it  was  enough  to  apply  the  ear  to  the  vertical 
board  of  the  instrument.  It  is  true  that  speech  was  not  re- 
produced, but  of  this  Mr.  Hughes  had  warned  me ;  it  was 
evident  that  with  this  arrangement  the  instrument  was  not 
sufficiently  sensitive. 

A  different  arrangement  of  the  microphone  is  required  for 
the  transmission  and  the  reproduction  of  speech  by  this  system, 
and  a  section  of  the  one  which  Mr.  Hughes  found  most  suc- 
cessful is  given  in  Fig.  45.  It  somewhat  resembles  Mr.  Hnghes's 


158 


THE   TELEPHONE. 


microphone  speaker,  placed  in  a  vertical  position,  and  the  fixed 
carbon  is  fastened  to  the  centre  of  the  stretched  membrane  of 

a  string  telephone.  The  ear 
or  mouth  tube  is  at  A,  the 
membrane  at  DD,the  carbon 
just  mentioned  at  C:  this 
carbon  is  of  metallized  char- 
coal prepared  from  deal,  and 
so  also  is  the  double  carbon, 
E,  which  is  in  contact  with 
it,  and  is  fastened  to  the  up- 
per end  of  the  little  bar,  G  I. 
The  whole  is  enclosed  in  a 
small  box,  and  the  pressure 
exerted  on  the  contact  of 
the  two  carbons  is  regulated 
by  a  spring,  R,  and  a  screw, 
FlG-  45'  H.  The  tube  of  the  tele- 

phone serves  as  an  acoustic  tube  for  the  listener,  and  Mr. 
Hughes's  speaker,  described  above,  acts  as  sender.  It  is  hardly 
necessary  to  say  that  the  two  instruments  are  placed  at  each 
end  of  the  circuit,  that  the  carbons  are  connected  with  the  two 
poles  of  a  battery  of  one  or  two  cells  of  bichromate  of  potash, 
or  two  Bunsen  or  six  Leclanche  cells,  and  the  two  instruments 
are  connected  by  the  line  wire.  Under  such  conditions,  con- 
versation may  be  exchanged,  but  the  sounds  are  always  much 
less  distinct  than  they  are  in  a  telephone. 

I  was  able  to  ascertain  this  fact  with  a  roughly  made  instru- 
ment brought  from  England  by  Mr.  Hughes.  MM.  Berjot, 
Chardin,  and  de  Meritens,  who  were  also  present  at  the  experi- 
ments, were  able  with  me  to  hear  speech  perfectly,  and  I  have 
since  successfully  repeated  the  experiment  alone,  but  it  does  not 
always  succeed,  and  under  its  present  conditions  the  instrument 
has  no  importance  in  a  scientific  point  of  view.  It  is  evident 


OTHER   SYSTEMS.  159 

that  the  instrument  can  dispense  with  any  support,  and  the 
little  box  then  forms  the  handle  of  the  instrument;  in  this 
case  the  two  binding  screws  are  placed  at  the  end  of  this  han- 
dle, as  in  a  telephone.  The  microphone  speaker  with  a  disk, 
represented  in  Fig.  5,  which  acts  as  sender  to  the  singing  con- 
denser, can  be  used,  when  properly  regulated,  as  a  receiving  mi- 
crophone. M.  Berjot  has  obtained  good  results  from  a  little 
instrument  of  the  same  kind  as  that  in  Fig.  45,  but  with  a 
metal  diaphragm,  and  the  microphonic  system  consists  of  a 
cylindrical  piece  of  carbon  resting  on  a  small  disk  of  the  same 
substance,  which  is  galvanized  and  soldered  to  the  diaphragm. 
The  whole  is  enclosed  in  a  small  round  box,  with  its  upper 
part  cut  in  the  form  of  a  mouth-piece. 

It  seems  that  all  microphone  senders  with -disks  can  repro- 
duce speech  more  or  less  perfectly ;  it  is  a  question  of  adjust- 
ing and  refining  the  carbon  points  of  contact.  A  weak  battery, 
consisting  of  a  single  Leclanche  cell,  is  better  for  these  instru- 
ments than  a  strong  battery,  precisely  because  of  the  effects  of 
oxidation  and  polarization,  which  are  so  energetically  produced 
at  these  points  of  contact  when  the  battery  is  strong. 

The  effects  of  the  microphone  receiver  explain  the  sounds, 
often  very  intense,  produced  by  the  Jablochkoff  candles  when 
they  are  influenced  by  electro  -  magnetic  machines.  These 
sounds  always  vibrate  in  unison  with  those  emitted  by  the  ma- 
chine itself,  and  they  result,  as  I  have  already  shown,  from  the 
rapid  magnetizations  and  demagnetizations  which  are  effected 
by  the  machine.  These  effects,  observed  by  M.  Marcel  Deprez, 
were  particularly  marked  in  M.  de  Meritens's  first  machines. 

Other  Arrangements  of  Microphones. — An  arrangement  such 
as  we  have  just  described  has  been  employed  by  M.  Carette  to 
form  an  extremely  powerful  microphone  speaker.  The  only 
difference  is  that  the  stretched  membrane  is  replaced  by  a  thin 
metallic  disk :  he  fastens  one  of  the  carbons  to  the  centre  of 
this  disk,  and  applies  to  it  the  other  carbon,  which  is  pointed, 


160  THE    TELEPHONE. 

and  held  by  a  porte-carbon  with  a  regulating  screw,  so  that  the 
pressure  which  takes  place  between  the  two  carbons  may  be 
regulated  at  pleasure.  By  this  arrangement  speech  may  be 
heard  at  a  distance  from  the  telephone.  In  other  respects  it 
resembles  the  telephone  sender  represented  in  Fig.  5. 

M.  de  Meritens  has  executed  the  system  represented,  Fig.  45, 
on  a  large  scale,  forming  the  tube,  A  B,  of  a  zinc  funnel  a  yard 
in  length,  and  in  this  way  he  has  been  able  to  magnify  the 
sounds,  so  that  a  conversation  held  in  a  low  voice,  three  or  four 
yards  from  the  instrument,  has  been  produced  in  a  telephone 
with  more  sonorous  distinctness.  The  instrument  was  placed 
on  the  floor  of  the  apartment,  with  the  opening  of  the  funnel 
above,  and  the  telephone  was  in  the  cellars  of  the  house. 

The  form  of  the  microphone  has  been  varied  in  a  thousand 
ways,  to  suit  the  purposes  to  which  it  was  to  be  applied.  In 
the  English  Mechanic  and  World  of  Science,  June  28th,  1878, 
we  see  the  drawings  of  several  arrangements,  one  of  which  is 
specially  adapted  for  hearing  the  steps  of  a  fly.  It  is  a  box, 
with  a  sheet  of  straw  paper  stretched  on  its  upper  part;  two 
carbons,  separated  by  a  morsel  of  wood,  and  connected  with 
the  two  circuit  wires,  are  fastened  to  it,  and  a  carbon  pencil, 
placed  crosswise  between  the  two,  is  kept  in  this  position  by  a 
groove  made  in  the  latter.  A  very  weak  battery  will  be  enough 
to  set  the  instrument  at  work,  and  when  the  fly  walks  over  the 
sheet  of  paper  it  produces  vibrations  strong  enough  to  react 
energetically  on  an  ordinary  telephone.  The  instrument  must 
be  covered  with  a  glass  globe.  When  a  watch  is  placed  on  the 
membrane,  with  its  handle  applied  to  the  morsel  of  wood  which 
divides  the  two  carbons,  the  noise  of  its  ticking  may  be  heard 
through  a  whole  room.  Two  carbon  cubes  placed  side  by  side, 
and  only  divided  by  a  playing-card,  may  also  be  used  instead 
of  the  arrangement  of  carbons  described  above.  A  semicircular 
cavity,  made  in  the  upper  part  of  the  two  carbons,  in  which  are 
placed  some  little  carbon  balls,  smaller  than  a  pea  and  larger 


TROUVE'S  SYSTEM.  161 

than  a  mustard-seed,  will  make  it  possible  to  obtain  multiple 
contacts  which  are  very  mobile  and  peculiarly  fit  for  telephon- 
ic transmissions.  This  arrangement  has  been  made  by  Mr.  T. 
Cuttriss. 

Several  other  arrangements  of  microphones  have  been  devised 
by  different  makers  and  inventors,  such  as  those  of  Messrs.  Va- 
rey,  Trouve,  Vereker,  De  Combettes,  Loiseau,  Lippens,  De  Cour- 
tois,  Pollard,  Voisin,  Dumont,  Jackson,  Paterson,  Taylor,  etc., 
and  they  are  more  or  less  satisfactory.  The  instruments  of 
MM.  Yarey,  Trouve,  Lippens,  and  De  Courtois  are  the  most  in- 
teresting, and  we  will  describe  them. 

M.  Varey's  microphone  consists  of  a  sounding-box  of  deal, 
mounted  in  a  vertical  position  on  a  stand,  and  two  microphones 
are  arranged  on  either  side  of  it,  with  vertical  carbons  united 
for  tension.  A  small  Gaiffe  cell  of  chloride  of  silver,  without 
liquid,  is  applied  to  the  standard  of  the  instrument,  and  is 
enough  to  make  it  work  perfectly.  This  system  is  extremely 
sensitive. 

M.  Trouve's  microphones,  represented  in  Figs.  46,  47,  48,  are 
extremely  simple,  so  that  he  is  able  to  sell  them  at  a  very  mod- 
erate price.  They  generally  consist  of  a  small  vertical  cylindri- 
cal box,  as  we  see  in  the  figure,  with  disks  of  carbon  at  its  two 


FIG.  46. 


ends,  which  are  united  by  a  carbon  rod,  or  by  a  metallic  tube 
tipped  with  carbon.     This  rod  or  tube  turns  freely  in  two  cav- 


162  THE   TELEPHONE. 

ities  made  in  the  carbons,  and  the  box,  while  acting  as  a  sound- 
ing-box, becomes  at  the  same  time  a  prison  for  the  insects 
whose  movements  and  noises  are  the  objects  of  study. 

These  boxes  may  be  suspended  on  a  cross-bar  (Fig.  4*7)  by 
the  two  communicating  wires,  so  as  to  be  completely  insulated. 
In  this  case  the  ticking  of  a  watch  placed  upon  the  board,  fric- 
tion, and  external  shocks  are  hardly  heard ;  but,  on  the  other 
hand,  the  sound  vibrations  of  the  air  alone  are  transmitted,  and 


FIG.  4T. 

they  acquire  great  distinctness.  We  have  often  repeated  these 
experiments,  and  have  always  found  that  the  tones  of  the  voice 
were  perfectly  preserved. 

The  model  represented,  Fig.  48,  is  still  more  simple,  and  ap- 
pears to  be  the  latest  development  of  this  kind  of  instrument. 
It  consists  of  a  stand  and  a  disk  united  by  a  central  rod.  The 
upper  disk  moves  round  the  central  rod,  and  permits  the  verti- 
cal carbon  to  assume  any  inclination  which  is  desired.  It  is 
evident  that  the  instrument  will  become  less  sensitive  when  the 
carbon  is  more  oblique. 

We  must  also  mention  a  very  successful  microphone  devised 
by  M.  Lippens.  It  is  a  slightly  made  box,  like  that  of  M.  Va- 


M.  LIPPENS'S   MICROPHONE.  163 

rey,  and  on  its  opposite  faces  there  are  applied,  on  two  frames 
left  empty  for  the  purpose,  two  thin  plates  of  hardened  caout- 
chouc, in  the  centre  of  which,  inside  the  box,  two  carbons  are 
fastened,  and  on  their  outer  surface  a  half-sphere  is  hollowed. 


FIG.  48.  • 

The  interval  between  the  two  carbons  hardly  amounts  to  two 
millimetres,  and  a  carbon  ball  is  inserted  into  the  two  cavities 
which  form  its  spherical  case.  This  ball  is  supported  by  a  spi- 
ral spring  which  can  be  extended  more  or  less  by  means  of  a 
wire  wound  on  a  windlass  which  is  fixed  above  the  instrument, 
like  the  spring  of  an  electric  telegraph  instrument.  By  means 
of  this  spring,  the  pressure  of  the  carbon  bait  against  the  sides 
of  the  cavity  which  contains  it  can  be  regulated  at  pleasure,  and 
the  sensitiveness  of  the  instrument  and  its  capacity  for  trans- 
mitting speech  can  be  adjusted.  Under  these  conditions,  the 
vibrations  of  the  caoutchouc  plates  directly  affect  the  micro- 
phone, and  the  currents  of  air  have  no  influence  on  it,  so  that 
the  effects  are  more  distinct.  It  is  so  sensitive  that  it  is  best 
for  the  speaker  to  place  himself  at  the  distance  of  at  least  fifty 
centimetres  from  the  instrument.  M.  Lippens's  instrument  is 
a  pretty  one,  mounted  on  a  wooden  stand  which  is  neatly 
turned. 

In  order  to  put  an  end  to  the  sputtering  usual  in  micro- 
phones, it  occurred  to  M.  de  Courtois  to  prevent  any  cessation 
of  contact  between  the  carbons  by  keeping  them  close  together, 


164  THE    TELEPHONE. 

and  to  effect  the  variations  of  resistance  necessary  for  articu- 
late sounds  by  making  them  slide  over  each  other,  so  as  to  in- 
sert a  shorter  or  longer  portion  of  the  carbon  in  the  circuit. 
For  this  purpose  a  vibrating  disk  is  placed  in  a  vertical  posi- 
tion in  a  rigid  frame,  and  a  small  conducting  rod,  terminated 
by  a  pointed  carbon,  is  applied  to  it,  with  this  carbon  point 
resting  on  another  flat  piece  of  carbon  placed  below  it.  Influ- 
enced by  the  vibrations  of  the  disk,  the  carbon  point  moves  to 
and  fro,  effecting  more  or  less  extensive  contacts  with  the  lower 
carbon,  and  thus  producing  variations  of  resistance  which  al- 
most correspond  to  the  range  of  vibrations  on  the  disk. 

Experiments  made  with  the  Microphone. — I  must  now  men- 
tion the  interesting  experiments  which  led  Mr.  Hughes  to  the 
invention  of  the  remarkable  instrument  of  which  we  have  spo- 
ken, as  well  as  those  undertaken  by  other  scientific  men,  either 
from  a  scientific  or  a  practical  point  of  view. 

Believing  that  light  and  heat  can  modify  the  conductivity 
of  bodies,  Mr.  Hughes  went  on  to  consider  whether  sound  vi- 
brations, transmitted  to  a  conductor  traversed  by  a  current, 
would  not  also  modify  this  conductivity  by  provoking  the 
contraction  and  expansion  of  the  conducting  molecules,  which 
would  be  equivalent  to  the  shortening  or  lengthening  of  the 
conductor  thus  affected.  If  such  a  property  existed,  it  would 
make  it  possible  to  transmit  sounds  t<?  a  distance,  since  varia- 
tions in  the  conductivity  would  result  from  variations  corre- 
sponding to  the  intensity  of  the  current  acting  on  the  tele- 
phone. The  experiment  which  he  made  on  a  stretched  metal 
wire  did  not,  however,  fulfil  his  expectation,  and  it  was  only 
when  the  wire  vibrated  so  strongly  as  to  break,  that  he  heard 
a  sound  at  the  moment  of  its  fracture.  When  he  again  joined 
the  two  ends  of  the  wire,  another  sound  was  produced,  and  he 
soon  perceived  that  imperfect  contact  between  the  two  broken 
ends  of  wire  would  enable  him  to  obtain  a  sound.  Mr.  Hughes 
was  then  convinced  that  the  effects  he  wished  to  produce  could 


HUGHES'S   EXPEKIMENTS. 


165 


only  be  obtained  with  a  divided  conductor,  and  by  means  of 
imperfect  contacts. 

He  then  sought  to  discover  the  degree  of  pressure  which  it 
was  most  expedient  to  exert  between  the  two  adjacent  ends  of 
the  wire,  and  for  this  purpose  he  effected  the  pressure  by  means 
of  weights.  He  ascertained  that  when  the  pressure  did  not  ex- 
ceed the  weight  of  an  ounce  on  the  square  inch  at  the  point  of 
connection,  the  sounds  were  reproduced  with  distinctness,  but 
somewhat  imperfectly.  He  next  modified  the  conditions  of 
the  experiment,  and  satisfied  himself  that  it  was  unnecessary  to 
join  the  wires  end  to  end  in  order  to  obtain  this  result.  They 
might  be  placed  side  by  side  on  a  board,  or  even  separated 
(with  a  conductor  placed  crosswise  between  them),  provided 
that  the  conductors  were  of  iron,  and  that  they  were  kept  in 
metallic  connection  by  a  slight  and  constant  pressure.  The  ex- 


FIG.  40. 

periment  was  made  with  three  Paris  points,  and  arranged  as  it 
appears  in  Fig.  49,  and  it  has  since  been  repeated  under  very 
favorable  conditions  by  Mr.  Willoughby  Smith  with  three  of 
the  so-called  rat-tail  files,  which  made  it  possible  to  transmit 
even  the  faint  sound  of  the  act  of  respiration.' 

1  Mr.  Willoughby  Smith  varied  this  experiment  by  placing  a  packet  of 


166     .  THE    TELEPHONE. 

He  afterward  tried  different  combinations  of  the  same  nat- 
ure, which  offered  several  solutions  of  continuity,  and  a  steel 
chain  produced  fairly  good  results,  but  slight  inflections,  like 
those  caused  by  the  timbre  of  the  voice,  were  not  reproduced, 
and  he  tried  other  arrangements.  He  first  sought  to  apply  me- 
tallic powders  to  the  points  of  contact ;  powdered  zinc  and  tin, 
known  in  commerce  under  the  name  of  white  bronze,  greatly 
increased  the  effects  obtained ;  but  they  were  unstable,  on  ac- 
count of  the  oxidation  of  the  contacts ;  and  it  was  in  seeking 
to  solve  this  difficulty,  as  well  as  to  discover  the  most  simple 
means  of  obtaining  a  slight  and  constant  pressure  on  the  con- 
tacts, that  Mr.  Hughes  was  led  to  the  arrangement,  previously 
described,  of  carbons  impregnated  with  mercury,  and  he  thus 
obtained  the  maximum  effect.1 

Mr.  Hughes  considers  that  the  successful  effects  of  the  micro- 
phone depend  on  the  number  and  perfection  of  the  contacts, 
and  this  is  doubtless  the  reason  why  some  arrangements  of  the 

silk  threads  coated  with  copper  on  the  disconnected  ends  of  the  circuit, 
which  were  arranged  at  right  angles  with  each  other.  Under  these  con- 
ditions the  instrument  became  so  sensitive,  that  the  current  of  air  pro- 
duced by  a  lamp  placed  above  the  system  caused  a  decided  crackling 
noise  in  the  telephone. 

1  Mr.  Hughes  observes  on  this  subject  that  carbon  is  a  valuable  mate- 
rial for  such  purposes,  since  it  does  not  oxidize,  and  its  effects  are  greater 
when  combined  with  mercury.  He  takes  the  prepared  charcoal  used  by 
artists,  brings  it  to  a  white  heat,  and  suddenly  plunges  it  in  a  bath  of  mer- 
cury, of  which  the  globules  instantly  penetrate  the  pores  of  charcoal,  and 
may  be  said  to  metallize  it.  He  also  tried  charcoal  coated  with  a  deposit 
of  platinum,  or  impregnated  with  chloride  of  platinum,  but  this  was  not . 
more  successful  than  the  former  method.  If  the  charcoal  of  fir-wood  is 
brought  to  a  white  heat  in  an  iron  tube,  containing  tin  and  zinc,  or  any 
other  metal  which  readily  evaporates,  it  is  metallized,  and  is  adapted  for 
use  if  the  metal  is  subdivided  in  the  pores  of  charcoal  and  not  combined 
with  it.  When  iron  is  introduced  into  carbon  in  this  way,  it  is  one  of  the 
most  effective  metals.  The  charcoal  of  fir-wood,  in  itself  a  bad  conductor, 
may  thus  acquire  great  conducting  power. 


' 

V        J  /> 
f\        «.- 

THEOR^.       S  ,  / ' ,     167 

V>         -     f  *     <"*  ' 

carbon  pencil  in  the  instrument  described  above^A^ce  more/''*, 
favorable  than  others.  Jf  \ 

In  order  to  reconcile  these  experiments  with  his  precoQceivol,/ 
ideas,  Mr.  Hughes  thought  that,  since  the  differences  of  resist-  *  « , 
ance  proceeding  from  the  vibrations  of  the  conductor  were 
only  produced  when  it  was  broken,  the  molecular  movements 
were  arrested  by  the  lateral  resistances  which  were  equal  and 
opposite,  but  that  if  one  of  these  resistances  were  destroyed, 
the  molecular  movement  could  be  freely  developed.  He  con- 
siders that  an  imperfect  contact  is  equivalent  to  the  suppres- 
sion of  one  of  these  resistances,  and  as  soon  as  this  movement 
can  take  place,  the  molecular  expansions  and  contractions 
which  result  from  the  vibrations  must  correspond  to  the  in- 
crease or  diminution  of  resistance  in  the  circuit.  We  need 
not  pursue  Mr.  Hughes's  theory  farther,  since  it  would  take 
too  long  to  develop  it,  and  we  must  continue  our  examination 
of  the  different  properties  of  the  microphone.1 

Carbon,  as  we  have  said,  is  not  the  only  substance  which  can 
be  employed  to  form  the  sensitive  organ  of  this  system  of 
transmission.  Mr.  Hughes  has  tried  other  substances,  includ- 
ing those  which  are  good  conductors,  such  as  metals.  Iron 
afforded  rather  good  results,  and  the  effect  produced  by  sur- 
faces of  platinum  when  it  was  greatly  subdivided  was  equal,  if 

1  Mr.  Hughes  remarks  that  the  vibrations  which  affect  the  microphone, 
even  in  speaking  at  a  distance  from  the  instrument,  do  not  proceed  from 
the  direct  action  of  the  sound  waves  on  the  contacts  of  the  microphone, 
but  from  the  molecular  vibrations  produced  by  it  on  the  board  which 
serves  to  support  the  instrument ;  he  shows,  in  fact,  that  the  intensity  of 
sounds  produced  by  the  microphone  is  in  proportion  to  the  size  of  the  sur- 
face of  this  board,  and  when  the  sending  microphone  is  enclosed  in  a 
cylindrical  case,  its  sensitiveness  is  not  much  diminished  if  the  surface  of 
the  box  enclosing  the  whole  is  sufficiently  large.  From  this  point  of  view 
he  has  sought  to  increase  the  sensitiveness  of  his  instruments  by  fixing 
the  frame  on  which  the  movable  parts  of  the  sender  and  receiver  revolve 
on  a  spring-plate. 


168  THE    TELEPHONE. 

not  superior,  to  that  furnished  by  the  mercurized  carbon.  Yet 
since  the  difficulty  of  making  instruments  with  this  metal  is 
greater,  he  prefers  the  carbon,  which  resembles  it  in  being 
incapable  of  oxidation. 

We  have  already  said  that  the  microphone  may  be  used  as 
a  thermoscope,  in  which  case  it  must  have  the  special  arrange- 
ment represented  in  Fig.  43.  Under  these  conditions,  heat, 
reacting  on  the  conductivity  of  these  contacts,  may  cause  such 
variations  in  the  resistance  of  the  circuit  that  the  current  of 
three  Daniell  cells  will  be  annulled  by  approaching  the  hand  to 
the  tube.  In  order  to  estimate  the  relative  -intensity  of  the 
different  sources  of  heat,  it  will  be  enough  to  introduce  into 
the  circuit  of  the  two  electrodes,  A  and  B,  Fig.  43,  a  battery, 
P,  of  one  or  two  Daniell  cells,  and  a  moderately  sensitive 
galvanometer,  G.  For  this  purpose  one  of  120  turns  will  suf- 
fice. When  the  deviation  decreases,  it  shows  that  the  source 
of  heat  is  superior  to  the  surrounding  atmosphere ;  and  con- 
versely, that  it  is  inferior  when  the  deviation  increases.  Mr. 
Hughes  says  that  the  effects  resulting  from  the  intervention 
of  sunshine  and  shadow  are  shown  on  the  instrument  by  con- 
siderable variations  in  the  deviations  of  the  galvanometer.  In- 
deed, it  is  so  sensitive  to  the  slightest  variations  of  temperature 
that  it  is  impossible  to  maintain  it  in  repose. 

I  have  repeated  Mr.  Hughes's  experiments  with  a  single 
Leclanche  cell,  and  for  this  purpose  I  employed  a  quill,  filled 
with  five  fragments  of  carbon,  taken  from  the  cylindrical  car- 
bons of  small  diameter  which  are  made  by  M.  Carre  for  the 
electric  light.  I  have  obtained  the  results  which  are  men- 
tioned by  Mr.  Hughes,  but  I  ought  to  say  that  the  experiment 
is  a  delicate  one.  When  the  pressure  of  the  fragments  of 
carbon  against  each  other  is  too  great,  the  current  traverses 
them  with  too  much  force  to  allow  the  calorific  effects  to  vary 
the  deviation  of  the  galvanometer,  and  when  the  pressure  is 
too  slight,  the  current  will  not  pass  through  them.  A  medium 


169 

degree  of  pressure  must,  therefore,  be  effected  to  insure  the 
success  of  the  experiment,  and  when  it  is  obtained,  it  is  ob- 
served that  on  the  approach  of  the  hand  to  the  tube,  a  devia- 
tion of  90°  will,  after  a  few  seconds,  diminish,  so  that  it  seems 
to  correspond  with  the  approach  or  withdrawal  of  the  hand. 
But  breathing  produces  the  most  marked  effects,  and  I  am 
disposed  to  believe  that  the  greater  or  less  deviations  produced 
by  the  emission  of  articulate  sounds,  when  the  different  letters 
of  the  alphabet  are  pronounced  separately,  are  due  to  more  or 
less  direct  emissions  of  heated  gas  from  the  chest.  It  is  cer- 
tain that  the  letters  which  require  the  most  strongly  marked 
sounds,  such  as  A,  F,  H,  I,  K,  L,  M,  N,  O,  P,  R,  S,W,  Y,  Z,  pro- 
duce the  greatest  deviations  of  the  galvanometric  needle. 

In  my  paper  on  the  conductivity  of  such  bodies  as  are  mod- 
erately good  conductors,  I  had  already  pointed  out  this  effect 
of  heat  upon  divided  substances,  and  I  also  showed  that  after 
a  retrograde  movement,  which  is  always  produced  at  once,  a 
movement  takes  place  in  an  inverse  direction  to  the  index  of 
the  galvanometer  when  heat  has  been  applied  for  some  in- 
stants, and  this  deviation  is  much  greater  than  one  which  is 
first  indicated. 

In  a  paper  published  in  the  American  Scientific  Journal, 
June  28th,  1878,  Mr.  Edison  gives  some  interesting  details  on 
the  application  of  his  system  of  a  telephonic  sender  to  measur- 
ing pressures,  expansions,  and  other  forces  capable  of  varying 
the  resistance  of  the  carbon  disk  by  means  of  greater  or  less 
compression.  Since  his  experiments  on  this  subject  date  from 
December,  1877,  he  again  claims  priority  in  the  invention  of 
using  the  microphone  as  a  thermoscope ;  but  we  must  observe 
that  according  to  Mr.  Hughes's  arrangement  of  his  instrument, 
the  effect  produced  by  heat  is  precisely  the  reverse  of  the  ef- 
fect described  by  Mr.  Edison.  In  fact,  in  the  arrangement 
adopted  by  the  latter,  heat  acts  by  increasing  the  conductivity 
acquired  by  the  carbon  under  the  increased  pressure  produced 

8 


170  THE   TELEPHONE. 

by  the  expansion  of  a  body  sensitive  to  heat ;  in  Mr.  Hughes's 
system,  the  effect  produced  by  heat  is  precisely  the  contrary, 
since  it  then  acts  only  on  the  contacts,  and  not  by  means  of 
pressure.  Therefore  the  resistance  of  the  microphone-thermo- 
scope  is  increased  under  the  influence  of  heat,  instead  of  being 
diminished.  This  contrary  effect  is  due  to  the  division  of 
some  substance  which  is  only  a  moderate  conductor,  and  I 
have  shown  that  under  such  conditions  these  bodies,  when  only 
slightly  heated,  always  diminish  the  intensity  of  the  current 
which  they  transmit.  I  believe  that  Mr.  Edison's  arrangement 
is  the  best  for  the  thermoscopic  instrument,  and  makes  it  pos- 
sible to  measure  much  less  intense  sources  of  heat.  Indeed  he 
asserts  that  by  its  aid  the  heat  of  the  luminous  rays  of  the 
stars,  moon,  and  sun  may  be  measured,  and  also  the  variations 
of  moisture  in  the  air,  and  barometric  pressure. 

This  instrument,  which  we  give,  Fig.  50,  with  its  several  de- 
tails, and  with  the  rheostatic  arrangement  employed  for  meas- 
uring, consists  of  a  metallic  piece,  A,  fixed  on  a  small  board,  C, 
and  on  one  of  its  sides  there  is  the  system  of  platinum  disks 
and  carbons  shown  in  Fig.  28.  A  rigid  piece,  G,  furnished 
with  a  socket,  serves  as  the  external  support  of  the  system,  and 
into  this  socket  is  introduced  the  tapering  end  of  some  sub- 
stance which  is  readily  affected  by  heat,  moisture,  or  barome- 
tric pressure.  The  other  extremity  is  supported  by  another 
socket,  I,  fitted  to  a  screw-nut,  H,  which  may  be  more  or  less 
tightened  by  a  regulating  screw.  If  this  system  is  introduced 
into  a  galvanometric  circuit,  a,  £>,  c,  i,  g,  provided  with  all  the 
instruments  of  the  electric  scale  of  measure,  the  variations  in 
length  of  the  substance  inserted  are  translated  by  greater  or 
less  deviations  of  the  galvanometric  needle,  which  follow  from 
the  differences  of  pressure  resulting  from  the  lengthening  or 
shortening  of  the  surface  capable  of  expansion  which  is  inserted 
in  the  circuit. 

The  experiments  on  the  microphone  made  in  London  at  the 


EFFECTS    OF   THE    MICROPHONE. 


171 


meeting  of  the  Society  of  Telegraphic  Engineers  on  May  25th, 
1878,  were  wonderfully  successful,  and  they  were  the  subject 
of  an  interesting  article  in  the  Engineer  of  May  31st,  which  as- 
serts that  the  whole  assembly  heard  the  microphone  speak,  and 


that  its  voice  was  very' like  that  of  the  phonograph.  When 
the  meeting  was  informed  that  these  words  had  been  uttered 
at  some  distance  from  the  microphone,  the  Duke  of  Argyll, 


172  THE    TELEPHONE. 

who  was  present,  while  admiring  the  important  discovery,  could 
not  help  exclaiming  that  this  invention  might  have  terrible 
consequences,  since,  for  instance,  if  one  of  Professor  Hughes's 
instruments  were  placed  in  the  room  in  Downing  Street,  in 
which  Her  Majesty's  ministers  hold  their  cabinet  council,  their 
secrets  might  be  heard  in  the  room  in  which  the  present  meet- 
ing took  place.  He  added  that  if  one  of  these  little  instru- 
ments were  in  the  pocket  of  Count  Schouvaloff,  or  of  Lord 
Salisbury,  we  should  at  once  be  in  possession  of  the  secrets  for 
which  all  Europe  was  anxiously  waiting.  If  these  instruments 
were  able  to  repeat  all  the  conversations  held  in  the  room  in 
which  they  stood,  they  might  be  really  dangerous,  and  the 
Duke  thought  that  Professor  Hughes,  who  had  invented  such 
a  splendid  yet  perilous  instrument,  ought  next  to  seek  an  anti- 
dote for  his  discovery.  Dr.  Lyon  Playfair,  again,  thought  that 
the  microphone  ought  to  be  applied  to  the  aerophone,  so  that, 
by  placing  these  instruments  in  the  two  Houses  of  Parliament, 
the  speeches  of  great  orators  might  be  heard  by  the  whole 
population  within  five  or  six  square  miles. 

The  experiments  lately  made  with  the  microphone  at  Halifax 
show  that  the  Duke  of  Argyll's  predictions  were  fully  justified. 
It  seems  that  a  microphone  was  placed  on  a  pulpit-desk  in  a 
church  in  Halifax,  and  connected  by  a  wire  about  two  miles 
long  with  a  telephone  placed  close  to  the  bed  of  a  sick  person, 
who  was  able  to  hear  the  prayers,  the  chanting,  and  the  sermon. 
This  fact  was  communicated  to  me  by  Mr.  Hughes,  who  heard 
it  from  a  trustworthy  source,  and  it  is  said  that  seven  patients 
have  subscribed  for  the  expense  of  an  arrangement  by  which 
they  may  hear  the  church  services  at  Halifax  without  fatigue. 

The  microphone  has  also  lately  been  applied  to  the  transmis- 
sion of  a  whole  opera,  as  we  learn  from  the  following  account 
in  the  Journal  Telegraphique,  Berne,  July  25th,  1878  : 

"A  curious  micro -telephonic  experiment  took  place  on 
June  19th  at  Bellinzona,  Switzerland.  A  travelling  company 


EXPERIMENT   AT  BELLINZONA.  173 

of  Italian  singers  was  to  perform  Donizetti's  opera,  "Don  Pas- 
quale,"  at  the  theatre  of  that  town.  M.  Patocchi,  a  telegraphic 
engineer,  took  the  opportunity  of  making  experiments  on  the 
combined  effects  of  Hughes's  carbon  microphone  as  the  send- 
ing instrument,  and  Bell's  telephone  as  the  receiver.  With 
this  object  he  placed  a  Hughes  microphone  in  a  box  on  the 
first  tier,  close  to  the  stage,  and  connected  it  by  two  wires, 
from  one  to  half  a  millimetre  in  thickness,  to  four  Bell  re- 
ceivers, which  were  placed  in  a  billiard-room  above  the  vesti- 
bule of  the  theatre,  and  inaccessible  to  sounds  within  the  thea- 
tre itself.  A  small  battery  of  two  cells,  of  the  ordinary  type 
used  in  the  Swiss  telegraphic  service,  was  inserted  in  the  cir- 
cuit, close  to  the  Hughes  microphone. 

"  The  result  was  completely  successful.  The  telephones  ex- 
actly reproduced,  with  wonderful  purity  and  distinctness,  the 
instrumental  music  of  the  orchestra,  as  well  as  the  voices  of  the 
singers.  Several  people  declared  that  they  did  not  lose  a  note 
of  either,  that  the  words  were  heard  perfectly ;  the  airs  were 
reproduced  in  a  natural  key,  with  every  variation,  whether 
piano  or  forte,  and  several  amateurs  assured  M.  Patocchi  that 
"by  listening  to  the  telephone  they  were  able  to  estimate  the 
musical  beauty,  the  quality  of  the  singers'  voices,  and  the  gen- 
eral effect  of  the  piece,  as  completely  as  if  they  had  been 
among  the  audience  within  the  theatre. 

"  The  result  was  the  same  when  resistances  equivalent  to  ten 
kilometres  were  introduced  into  the  circuit,  without  increasing 
the  number  of  cells  in  the  battery.  We  believe  that  this  is 
the  first  experiment  of  the  kind  which  has  been  made  in  Eu- 
rope, at  least  in  a  theatre,  and  with  a  complete  opera;  and 
those  who  are  acquainted  with  the  delicacy  and  grace  of  the 
airs  in  "  Don  Pasquale "  will  be  able  to  appreciate  the  sensi- 
tiveness of  the  combined  instruments  invented  by  Hughes  and 
Bell,  which  do  not  suffer  the  most  delicate  touches  of  this 
music  to  be  lost." 


174  THE    TELEPHONE. 

Although  experiments  with  the  microphone  are  of  such  re- 
cent date,  they  have  been  very  various,  and  among  other  curi- 
ous experiments  we  learn  from  the  English  newspapers  that 
the  attempt  has  been  made  to  construct  an  instrument  on  the 
same  principle  as  the  telephone,  which  shall  be  sensitive  to  the 
variations  of  light.  It  is  known  that  some  substances,  and 
particularly  selenium,  are  electrically  affected  by  light,  that  is, 
that  their  conductivity  varies  considerably  with  the  greater  or 
less  amount  of  light  which  is  shed  upon  them.  If,  therefore, 
a  circuit  in  which  a  substance  of  this  nature  is  inserted  is  ab- 
ruptly subjected  to  a  somewhat  intense  light,  the  increase  of 
resistance  which  results  from  it  ought  to  produce  a  powerful 
sound  in  a  telephone  inserted  in  the  circuit.  This  fact  has 
been  verified  by  experiment,  and  Mr.  Willoughby  Smith  infers 
from  it,  as  we  have  already  suggested,  that  the  effects  produced 
in  the  microphone  are  due  to  variations  of  resistance  in  the 
circuit,  which  are  produced  by  more  or  less  close  contacts  be- 
tween imperfect  conductors. 

In  order  to  obtain  this  effect  under  the  most  favorable  con- 
ditions, Mr.  Siemens  employs  two  electrodes,  consisting  of  net- 
work of  very  fine  platinum  wire,  fitting  into  each  other  like 
two  forks,  of  which  the  prongs  are  interlaced.  These  elec- 
trodes are  inserted  between  two  glass  plates,  and  a  drop  of 
selenium,  dropped  in  the  centre  of  the  two  pieces  of  network, 
connects  them  on  a  circular  surface  large  enough  to  establish 
sufficient  conductivity  in  the  circuit.  It  is  on  this  flattened 
drop  that  the  ray  of  light  must  be  projected. 

APPLICATIONS  OF  THE  MICROPHONE. 

The  applications  of  the  microphone  increase  in  number 
every  day,  and  in  addition  to  those  of  which  we  have  just 
spoken  there  are  others  of  really  scientific  and  even  of  practi- 
cal interest.  Among  the  number  is  the  use  which  can  be  made 
of  it  as  a  system  of  relays  for  telegraphy,  in  science  for  the 


APPLICATIONS    OF   THE    MICROPHONE.  175 

study  of  vibrations  imperceptible  to  our  senses,  in  medicine 
and  surgery,  and  even  in  manufactures. 

Its  Application  to  Scientific  Research. — We  have  seen  that 
several  physicists,  including  Messrs.  Spottiswoode,  Warwick, 
Rossetti,  Canestrelli,  Wiesendanger,  Lloyd,  Millar,  Buchin,  and 
Blyth,  have  been  able  to  hear  what  is  said  in  a  telephone 
which  has  no  iron  diaphragm,  but  it  was  so  difficult  to  estab- 
lish the  fact  that  it  has  been  often  disputed.  More  certain 
evidence  was  desirable,  and  the  microphone  is  an  opportune 
agent  for  affording  it. 

The  Telegraphic  Journal  of  September  1st,  1878,  observes 
that  M.  du  Moncel,  in  order  to  claim  the  victory  in  his  con- 
troversy with  Colonel  Navez,  had  still  to  show  that  the  sounds 
which  appeared  to  be  inarticulate  in  telephones  without  a  dia- 
phragm might  become  intelligible  if  they  were  intensified. 
This  has  been  done  for  him  by  the  use  of  Mr.  Hughes' s  micro- 
phone, and  the  following  experiments  wrere  made  for  the  pur- 
pose: 

1.  If  a  magnetizing  coil,  surrounding  a  bar  of  soft  iron,  is 
inserted  in  the  circuit  of  a  microphone,  with  a  battery  of  three 
cells,  the  ticking  of  a  watch  and  other  sounds  of  the  same 
kind  may  be  heard  on  approaching  the  ear  to  the  electro-mag- 
net which  has  been  thus  constituted.     It  is  true  that  these 
sounds  are  very  faint  when  they  are  not  amplified,  but  if  the 
electro  -  magnet  is  fastened  to  a  board,  and  a  second  micro- 
phone is  fixed  to  the  same  board,  the  sounds  produced  by  the 
electro-magnet  are  magnified,  and  become  distinctly  audible  in 
the  telephone  which  is  placed  in  connection  with  this  second 
microphone. 

2.  These  sounds  may  be  further  amplified  by  resting  one  of 
the  extremities  of  the  core  of  the  electro-magnet  on  one  of  the 
poles  of  a  permanent  magnet,  which  is  fixed  upon  the  board. 
Articulate  speech  may  then  be  heard  in  the  telephone  which 
is  placed  in   connection  with  the  microphone  resting  on  the 


176  THE    TELEPHONE. 

board,  and  the  point  at  issue  between  MM.  Navez  and  Du 
Moncel  is  completely  decided  in  this  way :  for  the  auxiliary 
microphone  can  only  propagate  and  amplify  the  vibration  of 
articulate  sounds,  which  are  communicated  by  the  bar  magnet 
of  the  coil  to  the  board  on  which  the  two  instruments  are 
placed.  In  this  way  it  would  be  possible  to  render  articulate 
sounds  perceptible  to  M.  Navez,  when  transmitted  by  the  bar 
magnet  of  a  telephone  without  a  diaphragm. 

3.  When  a  second  bar  magnet  rests  on  the  free  pole  of  the 
electro-magnet,  so  as  to  present  to  it  a  pole  of  the  same  nat- 
ure as  the  one  with  which  it  is  already  in  communication — in 
a  word,  if  a  bar  is  placed  between  the  two  poles  of  a  horseshoe 
electro-magnet,  the  effects  are  still  more  marked,  and  hence  it 
may  be  assumed  that  the  bar  reacts  as  an  armature,  by  concen- 
trating the  lines  of  magnetic  force  in  the  vicinity  of  the  helix. 

4.  When  the  two  poles  of  a  horseshoe  magnet  are  inserted 
together  inside  a  coil,  their  effects  are  equally  energetic,  al- 
though by  this  arrangement  one  of  the  poles  might  be  expect- 
ed to  neutralize  the  effect  of  the  other;  but  the  most  important 
effects  have  been  obtained  by  placing  an  armature  of  soft  iron 
across  the  poles  of  the  magnet  which  has  been  already  inserted 
in  the  coil.     Under  these  conditions  articulate  sounds  are  dis- 
tinctly heard. 

These  experiments  were  confirmed  by  Mr.  F.  Varley,  in  a  let- 
ter published  in  the  Telegraphic  Journal  of  September  15th, 
1878,  and  among  the  fresh  experiments  mentioned  by  him  we 
will  quote  those  which  he  made  with  an  iron  tube  inserted  in  a 
helix,  in  which  the  two  opposite  poles  of  two  bar  magnets  are 
introduced.  These  poles  are  only  separated  from  each  other 
by  the  interval  of  an  inch,  so  that  the  centre  of  the  iron  tube 
may  be  strongly  magnetized. 

Mr.  Varley  says  that  this  last  arrangement  reproduces  the 
articulate  sounds  which  issue  from  a  sending  microphone,  and 
this  experiment  is  more  decisive  than  that  of  Professor  Hughes ; 


HICROPHOXIC   RELAYS.  177 

in  which  case  it  might  be  supposed  that  the  bar  magnet,  rest- 
ing on  the  polar  end  of  an  electro-magnetic  bar,  was  only  a 
modification  of  the  disk  in  the  Bell  telephone,  set  in  vibration 
by  the  alternate  currents  passing  through  the  helix,  and  that 
these  vibrations  were  communicated  to  the  board,  and  became 
sensible  when  enlarged  by  the  microphone.  But  such  an  ob- 
jection cannot  be  alleged  in  the  case  of  the  arrangement  de- 
scribed above,  for  since  the  sound  is  produced  between  the  cur- 
rent passing  into  the  helix  and  the  magnetic  current  of  the  bar, 
it  can  only  be  the  result  of  a  vibration  produced  by  a  disturb- 
ance of  the  reciprocal  relations  subsisting  between  these  two 
elements.  Mr.  Varley  adds  that  these  experiments  confirm  M. 
du  Mon eel's  researches,  which  have  thrown  considerable  light 
upon  the  causes  which  are  at  work  in  the  action  of  the  speak- 
ing telephone,  and  with  which  we  have  hitherto  been  imper- 
fectly acquainted. 

Its  Application  to  Telephonic  Relays. — In  February,  1878, 1 
first  began  to  consider  the  mode  of  forming  telephonic  relays, 
but  I  was  checked  by  the  discovery  that  there  was  no  vibration 
in  the  receiving  telephone,  and  I  made  the  following  communi- 
cation on  the  subject  to  the  Academic  des  Sciences  on  February 
25th  :  "If  the  vibrations  of  the  disk  in  the  receiving  telephone 
were  the  same  as  those  of  the  sending  telephone,  it  is  easy  to 
see  that  if  a  telephone  with  a  local  battery,  acting  both  as 
sender  and  receiver,  were  substituted  for  the  receiving  tele- 
phone, it  might,  by  the  intervention  of  the  induction  coil,  act 
as  a  relay,  and  might  therefore  not  only  amplify  the  sound, 
but  also  transmit  it  to  any  distance.  It  is,  however,  doubtful 
whether  the  vibrations  of  the  two  corresponding  disks  are  of 
the  same  nature,  and  if  the  sound  be  due  to  molecular  contrac- 
tions and  expansions,  the  solution  of  the  problem  becomes  much 
more  difficult.  Here  is,  therefore,  a  field  for  experiments." 
These  experiments  have  been  successfully  made  by  Mr.  Hughes, 
who  acquainted  me  with  them  early  in  June,  1878,  and  they 

8* 


178  THE    TELEPHONE. 

led  to  the  discovery  of  a  most  interesting  system  of  microphonic 
relays. 

On  a  wooden  board  of  moderate  size,  such  as  a  drawing- 
board,  he  placed  a  microphone  with  a  carbon  brought  to  a  fine 
point  at  each  end,  and  fixed  in  a  vertical  position.  One  or  more 
telephones  were  placed  in  the  circuit,  with  their  membranes 
facing  the  board,  and  a  continuous  sound  was  heard,  sometimes 
resembling  a  musical  note,  sometimes  the  singing  of  boiling  wa- 
ter in  an  oven ;  and  the  sound,  which  could  be  heard  at  a  distance, 
went  on  indefinitely,  as  long  as  the  electric  force  was  exerted. 
Mr.  Hughes  explains  this  phenomenon  in  the  following  way : 

The  slightest  shock  which  affects  the  microphone  has  the 
effect  of  sending  currents,  more  or  less  broken,  through  the 
telephones,  which  transform  them  into  sound  vibrations,  and 
since  these  are  mechanically  transmitted  by  the  board  to  the 
microphone,  they  maintain  and  even  amplify  its  action,  and 
produce  fresh  vibrations  on  the  telephones.  Thus  a  fresh 
action  is  exerted  on  the  microphone,  and  so  on  indefinitely. 
Again,  if  a  second  microphone,  in  connection  with  another  tele- 
phonic circuit,  be  placed  upon  the  same  board,  we  have  an  in- 
strument which  acts  as  a  telephonic  relay,  that  is,  it  transmits 
to  a  distance  the  sounds  communicated  to  the  board,  and  these 
sounds  may  serve  either  as  a  call,  or  as  the  elements  of  a  mes- 
sage in  the  Morse  code,  if  a  Morse  manipulator  is  placed  in  the 
circuit  of  the  first  microphone.  Mr.  Hughes  adds  that  he  has 
made  several  very  successful  experiments  with  this  system  of 
instruments,  although  he  only  employed  a  Daniell  battery  of 
six  cells  without  any  induction  coil.  By  fastening  a  pasteboard 
tube,  forty  centimetres  in  length,  to  the  receiving  telephone,  he 
was  able  to  hear  in  all  parts  of  a  large  room  the  continuous 
sound  of  the  relay,  the  ticking  of  a  watch,  and  the  scratching 
of  a  pen  upon  paper.  He  did  not  try  to  transmit  speech,  since 
it  would  not  have  been  reproduced  with  sufficient  distinctness 
under  such  conditions. 


STETHOSCOPIC   MICROPHONE.  179 

Since  this  first  attempt,  Mr.  Hughes  has  arranged  another 
and  still  more  curious  system  of  microphonic  relays,  for  which 
two  microphones  with  vertical  carbons  are  required.  He  places 
two  microphones  of  this  description  on  a  board,  and  connects 
one  of  them  with  a  third  microphone,  which  acts  as  a  sender, 
while  the  second  is  in  communication  with  a  telephone  and  a 
second  battery :  in  this  way  the  words  uttered  before  the  sen- 
der are  heard  in  the  telephone,  without  employing  any  electro- 
magnetic organ  for  the  telephonic  relay. 

In  August,  1878,  Messrs.  Houston  and  Thomson  likewise  ar- 
ranged a  system  of  telephonic  relays,  which  only  differs  from 
that  of  Mr.  Hughes  in  the  particular  of  having  the  microphone 
fixed  on  the  diaphragm  of  the  telephone,  and  not  on  the  board 
beside  it.  The  system  consists  of  three  vertical  microphones, 
which  can  be  combined  for  tension  or  quantity,  according  to 
the  conditions  for  which  they  are  required.  The  model  of 
this  instrument  was  represented  in  the  Telegraphic  Journal  of 
August  15th,  1878,  to  which  we  must  refer  our  readers,  if  they 
wish  for  further  information  on  the  subject. 

Its  Application  to  Medicine  and  Surgery. — The  extreme 
sensitiveness  of  the  microphone  suggested  its  use  for  the  ob- 
servation of  sounds  produced  within  the  human  body,  so  that 
it  might  serve  as  a  stethoscope  for  listening  to  the  action  of 
the  lungs  and  heart.  Dr.  Richardson  and  Mr.  Hughes  are  now 
busy  in  the  attempt  to  carry  out  this  idea,  but  so  far  the  result 
is  not  very  satisfactory,  although  they  still  hope  to  succeed. 
Meanwhile,  M.  Ducretet  has  made  a  very  sensitive  stethoscopic 
microphone,  which  we  represent  in  Fig.  51.  It  consists  of  a 
carbon  microphone,  C  P,  with  a  simple  contact,  of  which  the 
lower  carbon,  P,  is  fitted  to  one  of  M.  Marais's  tambourines 
with  a  vibrating  membrane,  T.  This  tambourine  is  connected 
with  another,  T',  by  a  caoutchouc  tube,  which  is  to  be  applied 
to  the  different  parts  of  the  body  which  demand  auscultation, 
and  which  is  therefore  termed  the  tambour  explorateur.  The 


180 


THE   TELEPHONE. 


sensitiveness  of  the  instrument  is  regulated  by  means  of  a 
counterpoise,  P  O,  which  is  screwed  upon  the  arm  of  a  bent 
lever,  and  to  this  the  second  carbon,  C,  is  fixed.  The  extreme 


FIG.  51. 

sensitiveness  of  M.  Marais's  tambourines  in  transmitting  vibra- 
tions is  well  known,  and  since  their  sensitiveness  is  further  in- 
creased by  the  microphone,  the  instrument  becomes  almost  too 
impressionable,  since  it  reveals  all  sorts  of  sounds,  which  it  is 
difficult  to  distinguish  from  each  other.  Such  an  instrument 
can  only  be  of  use  when  intrusted  to  experienced  hands,  and  a 
special  education  of  the  organ  of  hearing  is  needful,  in  order 
to  turn  it  to  account. 


ITS    USE    IN   SURGERY.  181 

In  a  work  lately  published  by  M.  Giboux,  on  the  applica- 
tion of  the  microphone  to  medicine,  this  stethoscopic  system  is 
rather  severely  criticised,  and  not  without  reason,  if,  as  M.  Gi- 
boux asserts,  it  is  only  sensitive  to  the  movements  which  takes 
place  on  the  surface  of  the  body,  and  those  which  are  internal 
are  either  lost  or  altogether  changed  in  character.  But  with- 
out pronouncing  on  the  improvements  which  may  ultimately 
be  made  in  the  instrument,  M.  Giboux  thinks  that  its  most  im- 
portant use  in  medical  practice  consists  in  its  allowing  a  cer- 
tain number  of  students  to  observe,  with  the  professor,  the  dif- 
ferent sounds  of  the  body,  to  study  them  with  him  in  their  dif- 
ferent phases,  and  thus  to  profit  more  readily  by  his  teaching. 
A  microphonic  circuit  might  bifurcate  between  several  tele- 
phones, so  that  each  person  might  hear  for  himself  what  is 
heard  by  others. 

The  most  important  application  of  the  instrument  to  surgical 
purposes  has  lately  been  made  by  Sir  Henry  Thomson,  aided 
by  Mr.  Hughes,  for  the  examination  of  the  bladder  in  cases  of 
stone.  It  enables  him  to  ascertain  the  presence  and  precise 
position  of  calculi,  however  small  they  may  be.  For  the  pur- 
pose of  research,  he  uses  a  sound,  made  of  a  Maillechort  rod,  a 
little  bent  at  the  end,  and  placed  in  communication  with  a  sen- 
sitive carbon  microphone.  When  the  sound  is  moved  about 
in  the  bladder,  the  rod  comes  in  contact  with  stony  particles, 
even  if  they  are  no  larger  than  a  pin's  head,  and  friction  ensues, 
producing  in  the  telephone  vibrations  which  can  be  easily  dis- 
tinguished from  those  caused  by  the  simple  friction  of  the  rod 
on  the  soft  tissues  of  the  sides  of  the  bladder.  The  arrange- 
ment of  the  instrument  is  shown  in  Fig.  52.  The  microphone 
is  placed  in  the  handle  which  contains  the  sound,  and  is  the 
same  as  that  given  in  Fig.  42,  but  of  smaller  size,  and  the  two 
conducting  wires,  e,  which  lead  to  the  telephone,  issue  from  the 
handle  by  the  end,  a,  opposite  to  that,  bb,  to  which  the  sound, 
dd,  is  screwed.  As  this  instrument  is  not  intended  to  repro- 


182 


THE    TELEPHONE. 


duce  speech,  retort  carbons  instead  of  wood  carbons  may  be 
used. 

Some  deaf  people,  whose  sense  of  hearing  is  not  completely 
destroyed,  have  been  able  to  hear  by  an  expedient 
based  upon  the  principle  of  the  microphone.  For 
this  purpose  two  telephones,  connected  by  a  me- 
tallic crown,  which  is  placed  on  the  temples,  are 
applied  to  the  ears  of  the  deaf  person,  and  the 
telephones  are  placed  in  communication  with  a 
battery  microphone,  which  hangs  to  the  end  of 
a  double  conducting  wire.  The  deaf  man  keeps 
the  microphone  in  his  pocket,  and  presents  it  as 
an  acoustic  tube  to  the  person  who  wishes  to  con- 
verse with  him.  Mr.  Hughes's  speaker,  repre- 
sented by  Fig.  42,  is  the  one  used. 

Various  Applications. — The  microphone  may 
be  used  in  many  other  ways,  some  of  which  are 
suggested  in  the  English  Mechanic  of  June  21st, 
1878.  The  article  states  that,  by  means  of  this 
instrument,  engineers  will  be  able  to  estimate  the 
effects  of  the  vibrations  caused  on  old  and  new 
buildings  by  the  passage  of  heavy  loads ;  a  sol- 
dier will  be  able  to  discover  the  enemy's  ap- 
proach when  he  is  several  miles  off,  and  may 
even  ascertain  whether  he  has  to  do  with  artil- 
lery or  cavalry ;  the  approach  of  ships  to  the 
neighborhood  of  torpedoes  may  be  automatically 
heralded  on  the  coast  by  this  means,  so  that  an 
explosion  may  be  produced  at  the  right  moment. 

It  has  also  been  proposed  to  use  the  microphone  to  give 
notice  of  an  escape  of  gas  in  coal-mines.  The  gas,  in  escaping 
from  between  the  seams  of  coal,  makes  a  whistling  noise,  which 
might,  with  the  aid  of  the  microphone  and  telephone,  be  heard 
at  the  top  of  the  shaft.  Again,  it  has  been  suggested  that  the 


FIG.  52. 


DISTURBING   INFLUENCES.  183 

microphone  might  be  used  as  a  seismograph  to  reveal  the  sub- 
terranean noises  which  generally  precede  earthquakes  and  vol- 
canic eruptions,  and  which  would  be  much  intensified  by  this 
instrument.  It  might  even  be  of  use  to  Signor  Palmieri  for 
his  observations  in  the  Vesuvius  Observatory. 

The  microphone  has  also  been  used  by  Mr.  Chandler  Roberts 
to  render  the  diffusion  of  gaseous  molecules  through  a  porous 
membrane  sensible  to  the  ear. 

As  might  have  been  expected,  the  acclamation  with  which 
Mr.  Hughes' s  invention  was  received  led  to  the  assertion  of 

O 

other  claims  to  priority,  and  in  addition  to  that  of  Mr.  Edison, 
on  which  we  have  already  given  our  opinion,  there  are  several 
others,  showing  that  if  some  microphonic  effects  were  discover- 
ed at  different  times  before  the  date  of  Mr.  Hughes' s  discovery, 
they  could  not  have  been  considered  important,  since  they  were 
not  even  announced.  Among  the  number  was  that  of  Mr. 
AVentworth  Lascelles  Scott,  specified  in  the  Electrician  of  May 
25th,  1878,  and  that  of  M.  Weyher,  presented  to  the  Societe  de 
Physique,  Paris,  in  June,  1878.  Another,  made  by  M.  Dutertre, 
is  of  somewhat  greater  importance,  for  his  experiments  were 
reported  in  the  Rouen  papers  in  February  of  the  same  year: 
yet  there  is  no  just  ground  for  such  claims,  since  the  earliest 
date  of  his  experiments  is  subsequent  to  the  experiments  first 
made  by  Mr.  Hughes.  These  began  early  in  December,  1877, 
and  in  January,  1878,  they  were  exhibited  to  officials  of  the 
Submarine  Telegraph  Company,  as  Mr.  Preece  declared  in  a 
letter  addressed  to  the  several  scientific  men. 

EXTERXAL  IXFLUEXCE  OX  TELEPHOXIC  TRAXSMISSIOXS. 

The  obstacles  which  occur  in  telephonic  transmissions  pro- 
ceed from  three  causes:  1.  The  intensity  of  sound  is  diminish- 
ed by  the  loss  of  current  in  transmission — a  loss  which  is  much 
greater  in  the  case  of  induced  currents  than  in  those  received 
from  a  battery.  2.  Confusion  is  caused  by  the  influence  of  ad- 


184  THE   TELEPHONE. 

jacent  currents.  3.  The  induction  from  one  wire  to  another. 
This  last  influence  is  much  greater  than  is  usually  supposed. 
If  two  perfectly  insulated  wires  are  placed  side  by  side,  one  in 
communication  with  the  circuit  of  an  electric  bell,  and  the 
other  with  the  circuit  of  a  telephone,  the  latter  will  repeat  the 
sounds  of  the  bell  with  an  intensity  often  great  enough  to  act 
as  a  call  without  applying  the  instrument  to  the  ear.  MM. 
Pollard  and  Gamier,  in  their  interesting  experiments  with  the 
induced  currents  of  the  Ruhmkorff  coil,  have  ascertained  that 
in  this  way  not  merely  sounds  may  be  obtained  which  corre- 
spond with  the  induced  currents  resulting  from  the  action  of 
the  primary  current,  but  also  those  which  result  from  the  action 
of  the  secondary  current  on  other  helices,  which  are  termed 
currents  of  the  second  order.  These  different  reactions  fre- 
quently cause  the  telephonic  transmissions  made  on  telegraphic 
lines  to  be  disturbed  by  irregular  sounds,  arising  from  the 
electric  transmissions  on  adjoining  lines ;  but  it  does  not  ap- 
pear that  these  influences  altogether  neutralize  each  other,  so 
that  conversation  held  in  the  ordinary  way,  and  a  message  sent 
in  the  Morse  code,  may  be  heard  simultaneously. 

At  the  artillery  school,  Clermont,  a  telephonic  communica- 
tion has  been  established,  for  the  sake  of  experiments,  between 
the  school  and  the  butts,  which  are  at  a  distance  of  about  eight 
miles.  Another  communication  of  the  same  kind  has  been  es- 
tablished between  the  Clermont  Observatory  and  the  one  at 
Puy-de-D6me,  which  is  nearly  nine  miles  from  the  former. 
These  two  lines  are  carried  on  the  same  posts  for  a  course  of 
six  miles,  together  with  an  ordinary  telegraphic  wire,  and  for  a 
distance  of  330  yards  there  are  seven  other  such  wires.  The 
two  telephonic  wires  are  ssparated  from  each  other  by  a  space 
of  eighty-five  centimetres.  The  following  facts  have  been  ob- 
served under  these  conditions : 

1.  The  school  telephone  is  perfectly  able  to  read  off  from 
their  sound  the  Morse  messages  which  pass  through  the  two  ad- 


TELEPHONIC    CIRCUITS.  185 

jacent  telegraph  wires,  and  the  ticking  of  the  instrument  does 
not  at  all  interfere  with  the  vocal  communication  of  the  tele- 
phone, nor  render  it  inaudible. 

2.  The  two  adjacent  telegraphic  lines,  although  not  in  con- 
tact, confuse  their  messages  together,  and  it  has  sometimes  been 
possible  to  hear  messages  from  Puy-de-D6me  at  the  school 
through  the  wire  which  runs  to  the  butts,  although  the  distance 
between  the  two  lines  is  nowhere  less  than  eighty-five  cen- 
timetres. 

These  inconveniences  have  been  in  some  degree  remedied  by 
inserting  strong  resistances  in  the  circuit,  or  by  putting  the 
current  to  earth  at  some  distance  from  the  telephonic  stations. 

M.  Izarn,  Professor  of  Physics  at  the  Lycee,  Clermont,  holds 
that  telephonic  electric  currents  may  readily  be  turned  aside 
by  the  earth,  especially  if  in  the  course  of  their  passage  they 
encounter  metallic  conductors,  such  as  gas  or  water-pipes.  He 
writes  as  follows  on  the  subject,  in  a  paper  addressed  to  the 
Academic  des  Sciences,  on  May  13th,  1878:  "I  set  up  a  tele- 
phone in  the  Clermont  Lycee  with  a  single  wire,  more  than 
fifty  yards  in  length,  which  crosses  the  court-yard  of  the  Lycee, 
and  goes  from  the  laboratory,  where  it  is  suspended  to  a  gas- 
burner,  to  a  room  near  the  porter's  lodge,  where  it  is  suspended 
to  another  gas-burner.  When  I  applied  my  ear  to  the  tele- 
phone, I  could  distinctly  hear  the  telegraphic  signals,  Morse  or 
otherwise,  which  came  either  from  the  telegraph  office  at  Cler- 
mont, or  from  the  telephone  office  which  was  at  work  between 
the  School  of  Artillery  and  the  butts  below  Puy-de-D6me,  a 
distance  of  eight  miles.  I  could  overhear  words,  and  especially 
the  military  orders  issued  at  the  butts  for  the  purpose  of  being 
heard  at  the  school.  Yet  my  wire  is  perfectly  independent  of 
those  used  for  signalling,  and  is  even  very  remote  from  them ; 
but  as  the  wires  of  the  telegraph  office  and  of  the  School  of 
Artillery  go  to  earth  at  a  little  distance  from  the  gas-pipes,  it 
is  probable  that  this  phenomenon  is  caused  by  a  diversion  of 


186  THE    TELEPHONE. 

the  current  produced  in  my  wire,  by  means  of  the  earth  and 
the  network  of  metal  pipes." 

Mr.  Preece  made  the  same  remark  in  his  notice  of  "  some 
physical  points  connected  with  the  telephone."  Again,  we 
read  in  the  Telegraphic  Journal  of  June  15th,  1878,  that  in  a 
telephonic  concert,  transmitted  from  Buffalo  to  New  York,  the 
singers  at  Buffalo  were  heard  in  an  office  placed  outside  the 
telegraphic  circuit  in  which  the  transmission  was  effected.  On 
inquiry,  it  was  ascertained  that  the  wire  through  which  the 
telephonic  transmission  took  place  was  at  one  point  in  its 
course  close  to  the  one  which  directly  transmitted  the  musical 
sounds,  but  the  distance  between  the  two  wires  was  not  less 
than  ten  feet. 

When  the  circuits  are  altogether  metallic  there  is  much  less 
risk  of  confusion,  and  M.  Zetzche  declares  that  sounds  proceed- 
ing from  other  wires  are  in  this  case  little  heard,  and  then  only 
momentarily,  so  that  it  is  much  more  easy  to  hear  with  this  ar- 
rangement than  with  the  one  in  ordinary  use.  "  It  is  not,"  he 
says,  "  the  resistances  of  the  wire,  but  rather  the  diversions  of 
the  current  near  the  posts,  which  interfere  with  telephonic  cor- 
respondence on  long  lines  above  ground.  This  was  proved  by 
the  following  experiments :  I  connected  the  telegraphic  line 
from  Dresden  to  Chemnitz  with  a  line  from  Chemnitz  to  Leip- 
sic  (fifty-four  miles),  which  made  a  circuit  of  one  hundred  and 
three  miles,  going  to  earth  at  its  two  extremities.  There  was 
no  communication  between  Dresden  and  Leipsic,  but  Leipsic 
and  Dresden  could  communicate  with  ease,  in  spite  of  the 
greater  extent  of  line.  I  broke  the  connection  with  earth, 
first  at  Leipsic,  then  simultaneously  at  Leipsic  and  Dresden, 
and  I  observed  the  following  effects:  When  insulation  took 
place  at  Leipsic  only,  the  telephone  could  be  heard  at  the  sta- 
tions of  Dresden,  Riesa,  and  Wurzen  ;  when  the  line  was  in- 
sulated at  both  ends,  the  communication  was  good  between  the 
two  latter  stations,  but  it  was  observed  that  at  the  intermediate 


TELEPHONIC   CIRCUITS.  187 

station  the  words  spoken  at  Wurzen  were  more  distinctly 
heard  than  the  words  spoken  at  Riesa  were  heard  at  Wurzen. 
Since  the  distance  from  AVurzen  to  Leipsic  is  little  more  than 
half  that  from  Riesa  to  Dresden,  there  are  consequently  nearly 
twice  as  many  posts  on  the  latter  line,  which  carry  the  currents 
to  earth,  and  hence  I  conclude  that  these  diversions  of  current 
explain  the  possibility  of  conversing  on  an  insulated  line,  and 
also  why  sounds  are  more  distinctly  heard  at  the  Riesa  station 
in  consequence  of  the  greater  intensity  of  current  still  remain- 
ing on  the  line." 

Some  vibrations  also  result  from  the  action  of  currents  of 
air  on  telegraphic  wires,  which  produce  the  humming  sound  so 
well  known  on  some  lines,  and  these  may  also  react  on  the  tel- 
ephone ;  but  they  are  in  this  case  generally  mechanically  trans- 
mitted, and  they  may  be  distinguished  from  the  others,  if  the 
sounds  which  ensue  are  heard  after  the  telephone  is  excluded 
from  the  circuit  by  a  break  with  a  short  circuit,  and  after  the 
communication  to  earth  established  behind  the  telephone  has 
been  broken. 

The  induced  reactions  caused  by  the  line  wires  on  each  oth- 
er are  not  the  only  ones  which  may  be  observed  on  a  tele- 
phonic circuit :  every  manifestation  of  electricity  near  a  tele- 
phone may  produce  sounds  of  greater  or  less  force.  Of  this 
we  have  already  given  a  proof  in  M.  d'Arsonval's  experiments, 
and  others  by  M.  Demoget  demonstrate  the  fact  still  more 
clearly.  In  fact,  if  a  small  bar  magnet  provided  with  a  vibra- 
tor be  placed  before  one  of  the  telephones  of  a  telephonic  cir- 
cuit, and  the  vibrating  plate  of  the  telephone  be  removed,  in 
order  to  draw  away  the  sound  produced  by  the  vibrator,  its 
humming  noise  may  be  distinctly  heard  on  the  second  tele- 
phone of  the  circuit ;  a  noise  which  attains  its  maximum  when 
the  two  extremities  of  the  electro-magnet  are  at  their  nearest 
point  to  the  telephone  without  a  diaphragm,  and  it  is  at  its 
minimum  when  this  electro-magnet  is  presented  to  it  along  its 


188  THE    TELEPHONE. 

neutral  line.  M.  Demoget  supposes  that  the  action  which  is 
exerted  in  this  instance  is  that  of  a  magnet  exerting  two  in- 
ducing actions  which  are  opposite  and  symmetrical,  with  a 
field  limited  by  a  double  paraboloid,  and  with  an  axis,  accord- 
ing to  his  experiments,  which  extended  fifty -five  centimetres 
beyond  the  magnetic  core,  and  a  vertical  diameter  of  sixty 
centimetres.  He  believes  that  in  this  way  it  would  be  easy  to 
telegraph  on  the  Morse  system,  and  that,  in  order  to  do  so,  it 
would  only  be  necessary  to  apply  a  key  to  the  inducing  elec- 
tro-magnet. 

Mr.  Preece  points  out  three  ways  of  overcoming  the  diffi- 
culty presented  by  the  induced  reactions  caused  by  the  wires 
on  each  other : 

1.  By  increasing  the  intensity  of  the  transmitted  currents, 
so  as  to  make  them  decidedly  stronger  than  the  induced  cur- 
rents, and  to  reduce  the  sensitiveness  of  the  receiving  tele- 
phone. 

2.  To  place  the  telephonic  wire  beyond  the  range  of  induc- 
tion. 

3.  To  neutralize  the  effects  of  induction. 

The  first  mode  may  be  effected  by  Edison's  battery  system, 
and  we  have  seen  that  it  is  very  successful. 

In  order  to  put  the  second  mode  in  practice,  Mr.  Preece  says 
that  it  would  be  necessary  to  study  the  two  kinds  of  induction 
which  are  developed  on  telegraphic  lines :  electro-static  induc- 
tion, analogous  to  that  produced  on  submarine  cables,  and  elec- 
tro-dynamic induction,  resulting  from  electricity  in  motion. 
In  the  former  case,  Mr.  Preece  proposes  to  interpose  between 
the  telephone  wire  and  the  other  wires  a  conducting  body  in 
communication  with  the  earth,  capable  of  becoming  a  screen 
to  the  induction  by  itself  absorbing  the  electro-static  effects. 
He  says  that  this  might  be  accomplished  by  surrounding  the 
telegraphic  wires  adjacent  to  the  telephonic  wire  with  a  metal- 
lic envelope,  and  then  plunging  them  in  water.  He  adds  that 


EFFECTS    OF    INDUCTION.  189 

tbe  effects  of  static  induction  are  not  completely  destroyed  in 
tins  way,  since  tbe  substance  used  is  a  bad  conductor,  but  tbey 
are  considerably  reduced,  as  be  lias  proved  by  experiments  be- 
tween Dublin,  Holybead,  Manchester,  and  Liverpool.  In  tbe 
second  case,  Mr.  Preece  admits  tbat  an  iron  envelope  might 
paralyze  tbe  electro -dynamic  effects  produced  by  absorbing 
them,  so  that  if  insulated  wires  were  employed,  covered  with 
an  iron  case,  and  communicating  with  the  earth,  the  two  in- 
duced reactions  would  be  annulled.  We  will  not  follow  Mr. 
Preece  in  his  theory  as  to  these  effects — a  theory  which  seems 
to  us  open  to  question,  but  we  content  ourselves  with  pointing 
out  his  proposed  mode  of  attenuation. 

In  order  to  carry  out  the  third  expedient,  it  might  be 
thought  that  it  would  be  enough  to  employ  a  return  wire  in- 
stead of  going  to  earth,  for  under  such  conditions  the  currents 
induced  on  one  of  the  w7ires  would  be  neutralized  by  those  re- 
sulting from  the  same  induction  on  the  second  wire,  which 
would  then  act  in  an  opposite  direction  ;  but  this  mode  would 
only  be  successful  when  there  is  a  very  small  interval  between 
the  two  telephone  wires,  and  they  are  at  a  considerable  distance 
from  the  other  wires.  AVhen  this  is  not  the  case,  and  they  are 
all  close  together,  as  in  submarine  or  subterranean  cables,  con- 
sisting of  several  wires,  this  mode  is  quite  inefficient,  A  small 
cable,  including  two  conductors,  insulated  with  gutta-percha,  may 
be  successfully  carried  through  the  air. 

The  use  of  two  conductors  has  the  further  advantage  of 
avoiding  the  inconvenience  of  stray  currents  on  the  line  and 
through  the  earth,  which,  when  the  communications  to  earth 
are  imperfect,  permit  the  line  current  to  pass  more  or  less  easily 
into  tbe  telephonic  line. 

In  addition  to  the  disturbing  causes  in  telephonic  transmis- 
sion we  have  just  mentioned,  there  are  others  which  are  also 
very  appreciable,  and  among  them  are  the  accidental  currents 
which  are  continually  produced  on  telegraphic  lines.  These 


190  THE   TELEPHONE. 

currents  may  proceed  from  several  causes — at  one  time,  from  at- 
mospheric electricity ;  at  another,  from  terrestrial  magnetism ;  at 
another,  from  thermo-electric  effects  produced  upon  the  lines ;  at 
another,  from  the  hydro-electric  reactions  produced  on  the  wires 
and  disks  in  communication  with  the  earth.  These  currents 
are  always  very  unstable,  and  consequently  they  are  likely,  by 
reacting  on  the  transmitted  currents,  to  modify  them  so  as  to 
produce  sounds  upon  the  telephone.  Mr.  Preece  asserts  that 
the  sound  proceeding  from  earth  currents  somewhat  resembles 
that  of  falling  water.  The  discharges  of  atmospheric  elec- 
tricity, even  when  the  storm  is  remote,  produce  a  sound  which 
varies  with  the  nature  of  the  discharge.  When  it  is  diffused 
and  the  clap  takes  place  near  at  hand,  Dr.  Channing,  of  Provi- 
dence, United  States,  says  that  the  sound  resembles  that  pro- 
duced by  a  drop  of  fused  metal  when  it  falls  into  water,  or, 
still  more,  that  of  a  rocket  discharged  at  a  distance :  in  this 
case  it  might  seem  that  the  sound  would  be  heard  before  the 
appearance  of  the  flash,  which  clearly  shows  that  the  electric 
discharges  of  the  atmosphere  only  take  place  in  consequence  of 
an  electric  disturbance  in  the  air.  Mr.  Preece  adds  that  a  wail- 
ing sound  is  sometimes  heard,  which  has  been  compared  to 
that  of  a  young  bird,  and  which  must  proceed  from  the  in- 
duced currents  which  terrestrial  magnetism  produces  in  the 
metallic  wires  when  placed  in  vibration  by  currents  of  air. 

M.  Gressier,  in  a  communication  made  to  the  Academic  des 
Sciences  on  May  6th,  1878,  has  spoken  of  some  of  these  sounds, 
but  he  is  totally  mistaken  in  the  source  to  which  he  ascribes 
them. 

"  In  addition  to  the  crackling  sound  caused  by  the  working 
of  telegraph  instruments  on  the  adjacent  lines,  a  confused  mur- 
mur takes  place  in  the  telephone,  a  friction  so  intense  that  it 
might  sometimes  be  thought  that  the  vibrating  disk  was  split- 
ting. This  murmur  is  heard  more  by  night  than  by  day,  and 
is  sometimes  intolerable,  since  it  becomes  impossible  to  under- 


EFFECTS    OF   HEAT   AND   MO1STUHE.  191 

stand  the  telephone,  although  nothing  is  going  on  in  the  office 
to  disturb  the  sound.  The  same  noise  is  heard  when  only  one 
telephone  is  used.  A  good  galvanometer  inserted  in  the  cir- 
cuit reveals  the  presence  of  sensible  currents,  sometimes  in  one 
direction,  sometimes  in  another." 

I  studied  these  currents  for  a  long  time  with  the  galvanome- 
ter, and  made  them  the  subject  of  four  papers  which  were  laid 
before  the  Academic  des  Sciences  in  1872,  and  I  am  convinced 
that  they  have  in  general  nothing  to  do  with  atmospheric  elec- 
tricity, but  result  either  from  thermo-electric  or  hydro-electric 
influence.  They  take  place  constantly  and  in  all  weathers  on 
telegraph  lines,  whether  these  lines  are  insulated  at  one  end,  or 
in  contact  with  the  earth  at  both  ends.  In  the  first  case,  the 
polar  electrodes  of  the  couple  are  formed  by  the  telegraph  wire 
and  the  earth  plate,  generally  of  the  same  nature,  and  the  in- 
termediate conducting  medium  is  represented  by  the  posts 
which  support  the  wire  and  the  earth  which  completes  the 
circuit.  In  the  second  case,  the  couple  is  formed  in  almost  the 
same  way,  but  the  difference  in  the  chemical  composition  of 
the  ground  at  the  two  points  where  the  earth  plates  are  buried, 
and  sometimes  their  different  temperature,  exert  a  strong  influ- 
ence. If  only  the  first  case  be  considered,  it  generally  happens 
that  on  fine  summer  days  the  currents  produced  during  the 
day  are  inverse  to  those  which  are  produced  by  night,  and  vary 
with  the  surrounding  temperature  in  one  or  the  other  direction. 
The  presence  or  absence  of  the  sun,  the  passage  of  clouds,  the 
currents  of  air,  involve  abrupt  and  strongly  marked  variations, 
which  may  be  easily  followed  on  the  galvanometer,  and  which 
cause  more  or  less  distinct  sounds  in  the  telephone. 

During  the  day  the  currents  are  directed  from  the  telegraph 
line  to  the  earth  plate,  because  the  heat  of  the  wire  is  greater 
than  that  of  the  plate,  and  these  currents  are  then  thermo- 
electric. During  the  night,  on  the  other  hand,  the  wire  is  cool- 
ed by  the  dew,  which  causes  a  greater  oxidation  on  the  wire 


192  THE    TELEPHONE. 

than  that  which  takes  place  on  the  plate,  and  the  currents  then 
become  hydro-electric. 

I  say  more  about  these  currents,  because,  in  consequence  of 
a  mistaken  belief  as  to  their  origin,  it  has  been  supposed  that 
the  telephone  might  serve  for  the  study  of  the  variations  of 
the  atmospheric  electricity  generally  diffused  through  the  air. 
Such  an  application  of  the  telephone  would,  under  these  con- 
ditions, be  not  only  useless,  but  also  misleading,  by  inducing 
the  study  of  very  complex  phenomena,  which  could  lead  to 
nothing  more  than  I  have  already  stated  in  my  different  pa- 
pers on  the  subject. 

Certain  local  influences  will  also  produce  sounds  in  the  tele- 
phone. Thus  the  distention  of  the  diaphragm  by  the  moist 
heat  of  the  breath,  when  the  instrument  is  held  before  the 
mouth  in  speaking,  causes  a  perceptible  murmur. 

From  the  electro  -  static  reactions,  so  strongly  produced  on 
the  submarine  cables,  in  consequence  of  electric  transmissions, 
it  might  be  supposed  that  it  would  not  be  easy  to  hold  tele- 
phonic correspondence  through  this  kind  of  conductor,  and,  to 
ascertain  the  fact,  an  experiment  was  made  on  the  cable  be- 
tween Guernsey  and  Dartmouth,  a  distance  of  sixty  miles. 
Articulate  speech,  only  a  little  indistinct,  was,  however,  perfect- 
ly transmitted.  Other  experiments,  made  by  Messrs.  Preece 
and  Wilmot,  on  an  artificial  submarine  cable,  placed  in  condi- 
tions analogous  to  those  of  the  Atlantic  cable,  showed  that  a 
telephonic  correspondence  might  be  kept  up  at  a  distance  of 
a  hundred  miles,  although  the  effects  of  induction  were  appar- 
ent. At  the  distance  of  150  miles  it  was  somewhat  difficult 
to  hear,  and  the  sounds  were  very  faint,  as  if  some  one  were 
speaking  through  a  thick  partition.  The  sound  diminished 
rapidly  until  the  distance  of  200  miles  was  reached,  and  after 
that  it  became  perfectly  indistinct,  although  singing  could  still 
be  heard.  It  was  even  possible  to  hear  through  the  whole 
length  of  the  cable,  that  is,  for  3000  miles,  but  Mr.  Preece  be- 


TELEPHONIC   STATION.  193 

lieved  this  to  be  due  to  the  induction  of  the  condenser  on  it- 
self :  he  holds,  however,  that  singing  may  be  heard  at  a  much 
greater  distance  than  speech,  owing  to  the  more  regular  suc- 
cession of  electric  waves. 

Mr.  Preece  also  made  experiments  on  the  subterranean  tele- 
graphs between  Manchester  and  Liverpool,  a  distance  of  thirty 
miles,  and  found  no  difficulty  in  exchanging  correspondence ; 
and  it  was  the  same  with  the  cable  from  Dublin  to  Holyhead, 
a  distance  of  sixty-seven  miles.  This  cable  had  seven  conduct- 
ing wires,  and  when  the  telephone  was  connected  with  one  of 
them,  the  sound  was  repeated  through  all  the  others,  but  in  a 
fainter  degree.  "When  the  currents  of  the  telegraphic  instru- 
ments passed  through  the  wires,  the  induction  was  apparent, 
but  not  so  great  as  to  prevent  telephonic  communication. 

ESTABLISHMENT  OF  A  TELEPHONIC  STATION. 

Although  the  telephonic  system  of  telegraphy  is  very  sim- 
ple, yet  certain  accessory  arrangements  are  indispensable  for 
its  use.  Thus,  for  example,  an  alarum  call  is  necessary,  in  or- 
der to  know  when  the  exchange  of  correspondence  is  to  take 
place,  and  information  that  the  call  has  been  heard  is  like- 
wise necessary.  An  electric  bell  is  therefore  an  indispensable 
addition  to  the  telephone,  and  since  the  same  circuit  may  be 
employed  for  both  systems,  if  a  commutator  is  used,  it  was 
necessary  to  find  a  mode  of  making  the  commutator  act  au- 
tomatically, so  as  to  maintain  the  simple  action  of  the  system 
which  constitutes  its  principal  merit. 

MM.  Pollard  and  Garnier's  System. — With  this  object, 
MM.  Pollard  and  Gamier  devised  a  very  successful  arrange- 
ment last  March,  which  employs  the  weight  of  the  instrument 
to  act  upon  the  commutator. 

For  this  purpose  they  suspended  the  instrument  to  the  end 
of  a  spring  plate,  fastened  between  the  two  contacts  of  the 
commutator.  The  circuit  wire  corresponds  with  this  plate, 

9 


194  THE    TELEPHONE. 

and  the  two  contacts  correspond,  the  one  with  the  telephone, 
the  other  with  the  bell.  When  the  telephone  hangs  below  the 
spring-support,  that  is,  when  it  is  not  at  work,  its  weight  low- 
ers the  spring  plate  on  the  lower  contact,  and  the  communi- 
cation of  the  line  with  the  bell  is  established :  when,  on  the 
other  hand,  the  telephone  is  raised  for  use,  the  spring  plate 
touches  the  higher  contact,  and  communication  is  established 
between  the  line  and  telephone.  In  order  to  make  the  bell 
sound,  it  is  only  necessary  to  establish,  on  the  wire  which  con- 
nects the  line  with  the  bell  contact  of  the  commutator,  a  break- 
er which  can  both  join  and  break  the  current,  and  which  com- 
municates on  one  side  with  the  contact  of  the  bell,  and  on  the 
other  with  its  battery.  The  ordinary  push  of  an  electric  bell 
will  be  sufficient,  if  it  is  supplied  with  a  second  contact,  but 
MM.  Pollard  and  Gamier  wished  to  make  this  action  also  auto- 
matic, and  consequently  they  devised  the  arrangement  repre- 
sented in  Fia\  53. 


FIG.  53. 

In  tnis  system,  as  well  as  in  those  which  have  since  been 
devised,  two  telephones  are  employed,  one  of  which  is  con- 
stantly applied  to  the  ear,  and  the  other  to  the  mouth,  so  as  to 


BREGUET   AND    KOOSEVELT   SYSTEM.  195 

make  it  possible  to  speak  while  listening.  The  telephones  are 
supported  by  three  wires,  two  of  which  contain  flexible  con- 
ductors, while  the  third  only  acts  as  a  support. 

Two  of  the  four  wires  of  the  two  telephones  are  connected 
with  each  other,  and  the  other  two  are  connected  with  the  two 
binding  screws  of  the  commutator  t,  t' :  the  wires  without  con- 
ductors are  suspended  to  the  extremities  of  the  two  flexible 
plates,  /,  /',  which  correspond  with  earth  and  line. 

When  at  rest,  the  weight  of  the  telephones  presses  the  two 
plates,  /,  /',  on  the  lower  contacts,  S,  S',  but  when  the  instru- 
ments are  taken  up  these  plates  press  against  the  higher  con- 
tacts. 

The  two  bell  wires  terminate  on  the  lower  contacts,  those  of 
the  telephones  on  the  higher  contacts ;  and  one  of  the  poles  of 
the  battery  is  connected  with  the  lower  contact  on  the  left,  S', 
the  other  with  the  higher  contact  on  the  right,  T. 

When  at  rest,  the  system  is  applied  to  the  electric  bell,  and 
the  current  sent  from  the  opposite  station  will  follow  the  cir- 
cuit L  I S  S'  S'  /'  T,  so'that  the  call  will  be  made.  On  taking 
up  the  two  telephones,  the  circuit  of  the  bell  system  is  broken, 
and  that  of  the  telephones  is  established,  so  that  the  current 
follows  the  course  L  I T  1 1'  T'  /'  T.  If  only  one  telephone  is 
held  at  a  time,  the  current  is  sent  into  the  bell  system  of  the 
opposite  station,  and  follows  the  route  +  P  S  I L  T  /'  T' t  P — . 
In  this  way  the  three  actions  necessary  for  calling,  correspond- 
ing, and  enabling  the  corresponding  instrument  to  give  a  call, 
are  almost  involuntarily  made. 

System  by  MM.  Breguet  and  Roosevelt.  —  In  the  system 
established  by  the  Paris  agents  of  the  Bell  company,  the.  ar- 
rangement resembles  the  one  just  described,  except  that  there 
is  only  one  spring  commutator,  and  the  call  is  made  with  the 
push  of  an  ordinary  electric  bell.  A  mahogany  board  is  sus- 
pended from  the  wall,  and  on  it  are  arranged,  first,  the  ordinary 
electric  bell  system,  with  a  sending  push  fixed  below  it ;  second, 


196  THE   TELEPHONE. 

two  forks  supporting  two  telephones,  one  of  which  is  fastened 
to  the  bar  of  a  commutator,  arranged  as  a  Morse  key.  The 
two  telephones  are  connected  by  two  conducting  wires,  so  ar- 
ranged as  to  be  capable  of  extension,  and  two  of  their  four 
binding-screws  are  in  immediate  connection  with  each  other, 
and  the  Other  two  with  the  earth,  line,  and  battery,  by  means 
of  the  commutator,  the  sending  push,  and  the  bell  system. 
The  arrangement  is  shown  in  Fig.  54. 

The  commutator  A  consists  of  a  metallic  bar,  0,  c,  bearing 
the  suspension  fork  Of  one  of  the  telephones,  F',  below  its 
point  of  articulation :  it  ends  in  two  pins,  a  and  c,  below 
which  the  two  contacts  of  the  commutator  are  fixed,  and  a 
spring  compresses  the  lower  arm  of  the  bar,  so  as  to  cause  the 
other  arm  to  rest  constantly  on  the  higher  contact.  For 
greater  security,  a  steel  tongue,  a  6,  is  fastened  to  the  lower 
end  of  the  bar,  and  rubs  against  the  small  shaft  &,  which  is 
provided  with  two  insulated  contacts,  corresponding  to  those 
of  the  board.  The  bar  is  in  communication  with  the  line  wire 
by  means  of  the  call-push,  and  the  upper  of  the  two  contacts 
we  have  just  described  corresponds  with  one  of  the  telephone 
wires  which  is  inserted  in  the  same  circuit,  while  the  other  cor- 
responds with  the  bell  system,  S,  which  is  in  communication 
with  earth.  It  follows  from  this  arrangement,  that  when  the 
right  telephone  presses  its  whole  weight  on  the  support,  the 
bar  of  the  commutator  is  inclined  on  the  lower  contact,  and 
consequently  the  line  is  in  direct  communication  with  the  bell, 
so  that  the  call  can  be  made.  When,  on  the  other  hand,  the 
telephone  is  removed  from  its  support,  the  bar  rests  on  the 
higher  contact,  and  the  telephones  are  connected  with  the  line. 

Pressure  on  the  sending  push  serves  to  call  the  corresponding 
station :  the  connection  of  the  line  with  the  telephones  is  then 
broken,  and  it  is  established  with  the  battery  of  the  sending- 
station,  which  sends  its  current  through  the  bell  of  the  corre- 
sponding station.  In  order  to  obtain  this  double  effect,  the 


BREGUET   AND   ROOSEVELT   SYSTEM.  197 

contact  spring  of  the  sending  push  generally  rests  upon  a  con- 
tact fastened  to  a  piece  of  wood  shaped  like  a  joiner's  rule, 


FIG.  54. 


which  covers  it  in  front,  and  below  this  spring  there  is  a  second 
contact,  which  communicates  with  the  positive  pole  of  the  sta- 
tion battery.  The  other  contact  corresponds  with  the  line  wire, 


198 


THE    TELEPHONE. 


FIG.  55. 


and  a  connection  takes  place  between  the  earth  wire  and  the 
negative  pole  of  the  station  battery,  so  that  the  earth  wire  is 
common  to  three  circuits : 


EDISON'S  SYSTEM.  199 

1st.  To  the  telephone  circuit;  2d.  To  that  of  the  bell  sys- 
tem ;  3d.  To  that  of  the  local  battery. 

The  second  fork,  which  supports  the  telephone  on  the  right, 
is  fixed  to  the  board,  and  is  independent  of  any  electric  current. 

It  is  clear  that  this  arrangement  may  be  varied  in  a  thousand 
ways,  but  the  model  we  have  just  described  is  the  most  prac- 
tical. 

Edison's  System. — The  problem  becomes  more  complex  in 
the  case  of  battery  telephones,  since  the  battery  must  be  com- 
mon to  both  systems,  and  the  induction  coil  must  be  inserted 
in  two  distinct  circuits.  Fig.  55  represents  the  model  adopted 
in  Mr.  Edison's  telephone. 

In  this  arrangement  there  is  a  small  stand,  C,  on  the  mahog- 
any board  on  which  the  bases  of  the  two  telephones  rest.  The 
bell  system,  S,  is  worked  by  an  electro -magnetic  speaker,  P, 
which  serves,  when  a  Morse  key  is  added  to  the  system,  for  ex- 
change of  correspondence  in  the  Morse  code,  if  there  should  be 
any  defect  in  the  telephones,  or  to  put  them  in  working  order. 
Above  the  speaker  there  is  a  commutator  with  a  stopper,  D,  to 
adapt  the  line  for  sending  or  receiving,  with  or  without  the  bell ; 
and  below  the  stand,  C,  the  induction  coil,  destined  to  transform 
the  voltaic  currents  into  induced  currents,  is  arranged  in  a  small 
closed  box,  E. 

When  the  commutator  is  at  reception,  the  line  is  in  imme- 
diate correspondence  either  with  the  speaker  or  with  the  re- 
ceiving telephone,  according  to  the  hole  in  which  the  stopper 
is  inserted ;  when,  on  the  other  hand,  it  is  at  sending,  the  line 
corresponds  to  the  secondary  circuit  of  the  induction  coil. 
Under  these  conditions  the  action  is  no  longer  automatic  ;  but 
since  this  kind  of  telephone  can  only  be  usefully  employed  for 
telegraphy,  in  which  case  those  who  work  it  are  acquainted 
with  electric  apparatus,  there  is  no  inconvenience  in  this  com- 
plication. 


200  THE    TELEPHONE. 


CALL-BELLS  AND  ALARUMS. 

The  call-bells  applied  to  telegraphic  service  have  been  ar- 
ranged in  different  ways.  When  the  vibrating  bells  are  in  use, 
like  those  of  which  we  have  just  spoken,  it  is  necessary  to  use 
a  battery,  and  the  advantages  offered  by  telephones  with  in- 
duced currents  are  thus  sensibly  diminished.  In  order  to  dis- 
pense with  the  battery,  the  use  of  the  electro-magnetic  bell  has 
been  suggested. 

In  this  case  there  are  usually  two  bells,  with  a  hammer  oscil- 
lating between  them,  and  a  support  formed  of  the  polarized  ar- 
mature of  an  electro-magnet.  The  electro-magnetic  instrument 
is  placed  below  this  system ;  it  is  turned  by  a  winch,  and  sends 
the  currents,  alternately  reversed,  which  are  necessary  to  com- 
municate the  vibratory  movement  to  the  hammer,  and  this 
movement  is  enough  to  make  the  two  bells  tinkle.  Below  the 
winch  of  this  electro-magnetic  instrument  there  is  a  commuta- 
tor with  two  contacts,  which  adapts  the  instrument  for  sending 
or  receiving. 

M.  Mandroux  has  simplified  this  system,  and  has  reduced  it 
to  small  dimensions  by  the  following  arrangement :  He  fixes 
two  magnetic  cores,  furnished  with  coils,  on  each  of  the  two 
poles  of  a  horseshoe  magnet,  composed  of  two  bars  connected 
by  an  iron  coupler,  and  between  the  poles  expanded  by  these 
four  cores  he  inserts  an  armature,  within  which  there  is  a  steel 
spring  fastened  to  one  of  these  poles.  In  this  way  the  arma- 
ture is  polarized,  and  oscillates  under  the  influence  of  the  re- 
versed currents  transmitted  by  an  instrument  of  the  same  kind 
provided  with  an  induction  system.  These  oscillations  may 
have  the  effect  of  producing  the  sound  of  a  call-bell,  and  the 
induction  system  may  consist  of  a  manipulating  key,  fastened 
to  a  duplex  system  of  armature,  regularly  applied  to  the  mag- 
netic cores,  taken  in  pairs.  On  communicating  a  series  of 
movements  to  this  manipulator,  a  series  of  induced  currents  in 


WEINH  OLD'S  SYSTEM.  201 

an  inverse  direction  are  produced,  which  cause  the  armature  of 
the  corresponding  station  to  act  as  we  have  already  seen,  and 
which  may  even,  when  necessary,  furnish  a  series  of  Morse  sig- 
nals for  a  suitable  manipulation.  On  account  of  the  small  size 
of  this  system,  it  might  be  applied  to  the  telephonic  service  of 
the  army. 

The  Bell  Telephone  Company  in  Paris  has  arranged  another 
little  call-system  which  is  quite  satisfactory,  and  has  the  ad- 
vantage of  acting  as  a  telephone  at4he  same  time.  The  model 
resembles  the  one  we  have  termed  a  snuffbox  telephone,  and 
it  has  a  button  commutator  by  means  of  which  the  instrument 
is  placed  in  communication  with  the  electro-magnetic  system  of 
the  instrument,  or  with  a  battery  which  is  able  to  make  the 
telephone  vibrate  with  some  force.  To  make  a  call,  the  but- 
ton must  be  pressed,  and  the  battery  current  is  communicated 
to  the  corresponding  instrument,  which  begins  to  vibrate  when 
the  call  is  made;  and  when  notice  is  given  of  the  receipt  of 
the  signal,  the  pressure  on  the  button  is  removed,  and  it  be- 
comes possible  to  speak  and  receive  as  in  ordinary  telephones. 

M.  de  WeinholcCs  System. — M.  Zetzche  speaks  highly  of  an 
alarum  devised  by  Professor  A.  de  Weinhold,  which  resembles 
that  by  M.  Lorenz,  represented  in  Fig.  56.  Its  organ  of  sound 
consists  of  a  steel  bell,  T,  from  thirteen  to  fourteen  centimetres 
in  diameter,  and  toned  to  give  about  420  double  vibrations  in 
a  second.  "  Its  diameter  and  tone,"  he  says,  "  are  important, 
and  any  great  departure  from  the  rule  laid  down  diminishes 
the  effect.  The  opening  of  the  bell  is  below,  and  it  is  fixed  on 
a  stand  by  its  centre.  A  slightly  curved  bar  magnet,  provided 
at  its  two  ends  with  iron  appendices  enclosed  in  a  coil,  trav- 
erses the  stand.  The  bar  magnet  of  the  telephone  also  termi- 
nates in  an  iron  appendix  enclosed  in  a  coil.  In  both  cases 
the  changes  produced  in  the  magnetic  condition  appear  to  be 
more  intense  than  they  are  in  magnets  without  appendices. 
The  bar  magnet  is  placed  within  the  bell  in  the  direction  of 

9* 


202 


THE   TELEPHONE. 


one  of  its  diameters,  so  that  the  appendices  almost  touch  its 
sides. 

"  When  the  bell  is  struck  on  a  spot  about  90°  from  this 
diameter  with  a  wooden  clapper,  M,  which  acts  with  a  spring, 


FIG.  56. 

and  is  withdrawn  by  stretching  the  spring  and  then  letting  it 
go,  as  in  a  bell  for  the  dinner-table,  the  vibrations  imparted 
to  it  send  currents  into  the  coils,  and  these  currents  produce 
identical  vibrations  on  the  iron  disk  of  the  telephone,  which 
are  intensified  by  a  conical  resonator  fitted  to  the  telephone,  so 
as  to  be  easily  heard  some  paces  off.  For  ordinary  use,  the 
bell  coil  is  broken  into  a  short  circuit  by  means  of  a  metallic 
spring,  R ;  and  consequently,  when  the  bell  is  struck,  the  spring 
must  be  opened  so  as  not  to  break  the  circuit.  An  instrument 
of  the  same  kind  has  also  been  devised  by  Herr  W.  E.  Fein  at 
Stuttsrardt." 


DUTERTRE    AND   GOTJAULT's    SYSTEM. 


203 


MM.  Dutertre  and  Gouaulfs  System. — One  of  the  most  in- 
genious solutions  of  the  problem  of  making  the  telephone  call 
has  recently  been  proposed  by  MM.  Dutertre  and  Gouault. 
Figs.  57  and  58  represent  the  opposite  faces  of  the  instrument. 
It  consists  of  a  kind  of  snuffbox  telephone,  like  the  one  shown 
in  Fig.  26,  and  it  is  so  arranged  as  to  send  or  receive  the  call, 
according  to  the  way  in  which  it  is  placed  on  its  stand,  which 
is  only  an  ordinary  bracket  fastened  to  the  wall.  When  it  is 
placed  on  the  bracket  so  as  to  have  the  telephone  mouth-piece 
on  the  outside,  it  is  adapted  for  receiving,  and  can  then  give 
the  call.  When,  on  the  other  hand,  its  position  on  the  bracket 
is  reversed,  it  permits  the  other  station  to  make  the  call,  by 
producing  vibrations  on  a  vibrator  under  the  influence  of  a 
battery,  and  these  vibrations  reverberate  in  the  corresponding 


FIG.  57 


FIG.  6S. 


instrument  with  sufficient  force  to  produce  the  call.  If  the  in- 
strument is  taken  up,  and  the  finger  is  placed  on  a  small  spring 
button,  it  may  then  be  used  as  an  ordinary  telephone. 

In  this  instrument  the  magnet,  N  S  (Fig.  57),  is  snail-shaped, 
like  others  we  have  mentioned,  but  the  core  of  soft  iron,  S,  to 
which  the  coil  E  is  fastened,  can  produce  two  different  effects 
on  its  two  extremities.  On  the  one  side,  it  reacts  on  a  small 


204  THE    TELEPHONE. 

armature  which  is  fastened  to  the  end  of  a  vibrating  disk,  C, 
Fig.  58 ;  the  armature  is  placed  against  a  contact  fastened  to 
the  bridge  B,  and  constitutes  an  electro-magnetic  vibrator.  For 
this  purpose  the  bridge  is  in  metallic  communication  with  the 
coil  wire,  of  which  the  other  end  corresponds  with  the  line 
wire,  and  the  spring  C  is  mounted  on  an  upright,  A,  which 
also  supports  another  spring,  D  G,  acting  on  two  contacts,  one 
placed  at  G,  and  corresponding  to  the  earth  wire,  the  other  at 
H,  and  connected  with  the  positive  pole  of  the  battery.  A 
small  movable  button,  which  passes  through  a  hole  in  the  lid  of 
the  box,  and  projects  beyond  it,  is  fixed  at  G,  and  all  this  part 
of  the  instrument  faces  the  bottom  of  the  box.  The  upper 
part  consists  of  the  vibrating  disk  and  the  mouth-piece,  so  that 
the  mechanism  we  have  described  is  all  mounted  on  an  inner 
partition  forming  a  false  bottom  to  the  box. 

When  the  box  rests  upon  its  base,  on  the  side  shown  in  Fig. 
58,  the  button  at  G  presses  on  the  spring  D  G,  and  raises  it  so 
as  to  break  the  connection  with  the  battery ;  the  coil  of  the  in- 
strument is  then  united  to  the  circuit,  and  consequently  receives 
the  transmitted  currents,  which  follow  this  route :  line  wire, 
coil  E,  bridge  B,  spring  C,  spring  D  G,  earth  contact.  If  these 
currents  are  transmitted  by  a  vibrator,  they  are  strong  enough 
to  produce  a  noise  which  can  be  heard  in  all  parts  of  a  room, 
and  consequently  the  call  may  be  given  in  this  way.  If  the 
currents  are  due  to  telephonic  transmission,  the  instrument  is 
applied  to  the  ear,  care  being  taken  to  put  the  finger  on  the 
button  G,  and  the  exchange  of  correspondence  takes  place  as  in 
ordinary  instruments ;  but  it  is  simpler  and  more  manageable 
to  insert  a  second  telephone  in  the  circuit  for  this  purpose. 
When  the  box  is  inverted  on  its  mouth-piece,  and  the  button 
G  ceases  to  press  on  the  spring  D  G,  the  battery  current  reacts 
on  the  vibrator  of  the  instrument,  and  sends  the  call  to  the  cor- 
responding station,  following  this  route :  I  D  A  C  B  E,  line, 
earth,  and  battery ;  and  the  call  goes  on  until  the  correspond- 


'-,.'** 

f,  ' ''/•??»  'l  /«• 

\  *  A' 

ent  breaks  the  current  by  taking  up  his  insirament^Jirfs/warn-     / '  \ . 

ing  the  other  that  he  is  ready  to  listen.  ^  ^ /  * 

System  of  M,  Puluj. — There  is  yet  another  call  system,  <fo-  \  V 
vised  by  M.  Puluj.  It  consists  of  two  telephones  without  mouth-  '  ' . 
pieces,  connected  together,  and  with  coils  placed  opposite  the 
branches  of  two  tuning-forks,  tuned  as  nearly  as  possible  to  the 
same  tone.  A  small  metal  bell  is  fixed  between  the  opposite 
faces  of  the  tuning-forks,  and  a  wire  stretched  near  them  is  pro- 
vided with  a  small  ball  in  contact  with  their  branches.  "When 
the  tuning-fork  at  the  sen  ding-station  is  put  in  vibration  by 
striking  it  with  an  iron  hammer  covered  with  skin,  the  tuning- 
fork  at  the  other  station  vibrates  also,  and  its  ball  strikes  upon 
the  bell.  As  soon  as  the  signal  is  returned  by  the  second  sta- 
tion, mouth-pieces  with  iron  diaphragms  are  fastened  to  the  tel- 
ephones, and  the  correspondence  begins.  It  seems  that,  by  the 
use  of  a  resonator,  the  sound  which  reaches  the  receiving-sta- 
tion may  be  so  intensified  as  to  become  audible  in  a  large  hall, 
and  the  bell  signal  may  be  heard  in  an  adjoining  room,  even 
through  a  closed  door. 

Mr.  Alfred  Chiddey's  System. — This  arrangement  consists 
of  a  slender  copper  tube,  eight  inches  long,  and  with  an  orifice 
of  one-thirtieth  of  an  inch,  of  which  the  lower  end  is  soldered 
to  the  diaphragm  of  a  telephone.  A  branch  joint,  to  which  an 
India-rubber  tube  is  fitted,  connects  it  with  a  gas-jet,  which  is 
lighted  and  surrounded  with  a  lamp  shade,  in  such  a  way  as 
to  make  it  produce,  under  given  conditions,  sounds  resembling 
those  of  the  singing  flames.  A  perfectly  similar  system  is  ar- 
ranged at  the  other  end  of  the  line,  in  such  a  way  that  the 
sounds  emitted  in  each  case  shall  be  precisely  in  unison.  If 
the  two  systems  are  so  regulated  as  not  to  emit  sounds  in  their 
normal  condition,  they  can  be  made  to  sing  by  causing  a  tun- 
ing-fork in  the  vicinity  of  one  or  the  other  to  vibrate  the  same 
note,  and  then  the  corresponding  flame  will  begin  to  sing,  pro- 
ducing a  vibration  in  the  diaphragm  of  the  telephone  with 


206  THE    TELEPHONE. 

which  it  is  in  correspondence,  and  hence  will  follow  the  vibra- 
tion of  the  diaphragm  of  the  other  telephone,  and  consequently 
the  vibration  of  the  flame  of  the  calling  instrument.  In  this 
way  the  call  signal  may  be  made  without  the  intervention  of 
any  battery. 

APPLICATIONS  OF  THE  TELEPHONE. 

The  applications  of  the  telephone  are  much  more  numerous 
than  might  be  supposed  at  the  first  glance.  As  far  as  the  tele- 
graphic service  is  concerned,  its  use  must  evidently  be  rather 
limited,  since  it  cannot  register  the  messages  sent,  and  the 
speed  of  transmission  is  inferior  to  that  of  the  improved  sys- 
tem of  telegraphs ;  yet  in  many  cases  it  would  be  very  valuable, 
even  for  a  telegraphic  system,  since  it  is  possible  to  work  it 
without  any  special  telegraphic  training.  The  first  comer  may 
send  and  receive  with  the  telephone,  and  this  is  certainly  not 
the  case  even  with  the  simplest  forms  of  telegraphic  instru- 
ments. This  system  is,  therefore,  already  in  use  in  public  offices 
and  factories,  for  communication  in  mines,  for  submarine  works, 
for  the  navy,  especially  when  several  vessels  manosuvre  in  the 
same  waters,  some  towed  by  others ;  finally,  for  military  pur- 
poses, either  to  transmit  orders  to  different  corps,  or  to  com- 
municate with  schools  of  artillery  and  rifle  practice.  In  Amer- 
ica the  municipal  telegraphic  service  and  that  of  telegraphs  lim- 
ited to  the  area  of  towns  are  conducted  in  this  way,  and  it  is 
probable  that  this  system  will  soon  be  adopted  in  Europe.  In- 
deed, a  service  of  this  kind  was  established  in  Germany  last 
autumn  at  the  telegraph  offices  of  some  towns,  and  the  Lon- 
don Post-office  is  now  thinking  of  establishing  it  in  England. 

But,  besides  its  use  for  the  purposes  of  correspondence,  the 
telephone  can  be  useful  to  the  telegraphic  service  itself  by  af- 
fording one  of  the  simplest  means  of  obtaining  a  number  of 
simultaneous  transmissions  through  the  same  wire,  and  even  of 
being  combined  in  duplex  with  the  Morse  telegraphs.  Its  ap- 


SIMULTANEOUS   TRANSMISSION.  207 

plications  in  the  microphonic  form  are  incalculable,  and  the 
proverb  which  declares  that  "  walls  have  ears"  may  in  this  way 
be  literally  true.  It  is  alarming  to  think  of  the  consequences 
of  such  an  indiscreet  organ.  Diplomatists  must  certainly  re- 
double their  reserve,  and  tender  confidences  will  no  longer  be 
made  with  the  same  frankness.  On  this  point  we  cannot  think 
that  much  will  be  gained,  but,  on  the  other  hand,  the  physician 
will  probably  soon  make  use  of  this  invention  to  ascertain  more 
readily  the  processes  going  on  within  the  human  body. 

APPLICATION  OF  THE  TELEPHONE  TO  SIMULTANEOUS 
TELEGRAPHIC  TRANSMISSIONS. 

The  simultaneous  transmission  of  several  messages  through 
the  same  wire  is  one  of  the  most  curious  and  important  appli- 
cations of  the  telephone  to  telegraphic  instruments  which  can 
be  made,  and  we  have  seen  that  it  was  this  application  which 
led  Messrs.  Gray  and  Bell  to  the  invention  of  speaking  tele- 
phones. The  admiration  which  these  instruments  have  excited 
has  thrown  the  original  idea  into  the  background,  although  it 
has  perhaps  a  more  practical  importance.  We  will  now  con- 
sider these  systems. 

An  articulating  telephone  is  not  necessary  in  order  to  obtain 
simultaneous  transmission :  the  musical  telephones  devised  by 
MM.  Petrina,  Gray,  Froment,  etc.,  are  quite  sufficient,  and  a  brief 
explanation  of  their  principle  will  make  this  intelligible.  Sup- 
pose that  there  are  seven  electro-magnetic  vibrators  at  the  two 
corresponding  stations,  which  are  tuned  with  the  same  tuning- 
fork  on  the  different  notes  of  the  scale,  and  suppose  that  a  key- 
board, resembling  the  Morse  telegraph  key,  is  arranged  so  that, 
by  lowering  the  keys,  electric  reaction  takes  place  on  each  vi- 
brator :  it  is  easy  to  see  that  these  vibrators  may  be  made  to 
react  in  the  same  way  on  the  corresponding  vibrators  of  the 
opposite  station ;  but  they  must  be  tuned  on  the  same  note, 
and  the  sounds  emitted  will  continue  while  the  keys  are  low- 


208  THE   TELEPHONE. 

ered.  By  keeping  them  down  for  a  shorter  or  longer  time,  the 
long  or  short  sounds  which  constitute  the  elements  of  tele- 
graphic language  in  the  Morse  system  may  be  obtained,  and 
consequently  an  audible  transmission  becomes  possible.  Let 
us  now  suppose  that  a  telegraphist  accustomed  to  this  mode  of 
transmission  is  placed  before  each  of  the  vibrators,  and  that 
they  transmit  different  messages  at  the  same  moment  in  this 
way :  the  telegraphic  wire  will  be  instantaneously  traversed  by 
seven  currents,  broken  and  massed  upon  each  other,  and  they 
might  be  expected  to  produce  a  medley  of  confused  sounds  on 
the  vibrators  at  the  receiving-station ;  but  since  they  each  har- 
monize with  the  corresponding  vibrator,  they  have  no  sensible 
influence  except  on  those  for  which  they  are  intended.  The 
dominant  sound  may  be  made  still  more  distinct  by  applying  a 
Helmholtz  resonator  to  each  vibrator  j1  that  is,  an  acoustic  in- 
strument which  will  only  vibrate  under  the  influence  of  the 
note  to  which  it  is  tuned.  In  this  way  it  is  possible  to  select 
the  transmitted  sounds,  and  only  to  allow  each  employe  to  hear 
that  which  is  intended  for  him.  Consequently,  however  con- 
fused the  sounds  may  be  on  the  receiving  vibrators,  the  person 
to  whom  do  is  assigned  will  only  receive  do  sounds,  the  person 
to  whom  sol  is  assigned  will  only  receive  sol  sounds,  so  that 


1  Helmholtz's  resonator  is  based  upon  the  principle  that  a  volume  of  air 
contained  in  an  open  vase  emits  a  certain  note  when  placed  in  vibration, 
and  that  the  height  of  the  note  depends  on  the  size  of  the  vase  and  of  its 
opening.  Helmholtz  makes  use  of  a  globe  with  a  large  opening  on  one 
side  and  a  small  one  on  the  other,  and  the  small  one  is  applied  to  the  ear. 
If  a  series  of  musical  notes  take  place  in  the  air,  the  one  which  is  in  har- 
mony with  the  fundamental  note  of  the  globe  is  intensified,  and  can  be  dis- 
tinguished from  the  rest.  The  same  effect  takes  place  when,  on  singing  to 
a  piano  accompaniment,  some  strings  are  heard  to  vibrate  more  strongly 
than  others,  namely,  those  which  vibrate  in  unison  with  the  sounds  emitted. 
The  resonators  are  made  in  various  ways ;  those  most  generally  used  ara 
cases  of  different  lengths,  which  also  serve  as  sounding-boxes. 


ORIGIN    OF   THE    PRINCIPLE.  209 

correspondence  may  be  carried  on  as  well  as  if  they  had  each  a 
special  wire. 

In  the  mode  we  have  described,  this  telegraphic  system  only 
admits  of  audible  transmissions,  and  consequently  cannot  reg- 
ister messages.  To  supply  this  defect,  it  has  been  suggested 
to  make  the  receiving  vibrators  react  on  registers,  so  arranging 
the  latter  that  their  electric  organ  may  present  such  magnetic 
inertia  that,  when  it  is  influenced  by  the  vibrations  of  sound, 
its  effect  may  be  maintained  throughout  the  time  of  vibration. 
Experiments  show  that  a  Morse  receiver,  worked  by  the  current 
of  a  local  battery,  will  be  enough  for  this  purpose ;  so  that  if 
the  musical  vibrator  is  made  to  react  as  a  relay,  that  is,  on  a 
contact  in  connection  with  the  local  battery  and  the  receiver, 
the  dots  and  dashes  may  be  obtained  on  it  which  are  the  con- 
stituent elements  of  the  Morse  code. 

On  these  principles,  and  considering  that  the  musical  spaces 
separating  the  different  notes  of  the  scale  are  such  as  may  be 
easily  distinguished  by  the  resonator,  seven  simultaneous  trans- 
missions may  be  obtained  on  the  same  wire;  but  experience 
shows  that  it  is  necessary  to  be  content  with  a  much  smaller 
number.  Yet  this  number  may  easily  be  doubled  by  apply- 
ing the  mode  of  transmission  in  an  opposite  direction  to  the 
system. 

Mr.  Bell  states  that  the  idea  of  applying  the  telephone  to 
multiple  electric  transmissions  occurred  simultaneously  to  M. 
Paul  Lacour  of  Copenhagen,  to  Mr.  Elisha  Gray  of  Chicago, 
to  Mr.  Varley  of  London,  and  to  Mr.  Edison  of  New  York ; 
but  there  is  some  confusion  here,  for  we  have  already  seen, 
from  reference  to  the  patents,  that  Mr.  Yarley's  system  dates 
from  1870 ;  that  of  M.  Paul  Lacour  from  September,  1874 ;  that 
of  Mr.  Elisha  Gray  from  February,  1875;  and  those  of  Messrs. 
Bell  and  Edison  were  still  later.  Yet  it  appears  from  Mr. 
Gray's  specification  that  he  was  the  first  to  conceive  and  exe- 
cute instruments  of  the  kind.  In  fact,  in  a  specification  drawn 


210  THE    TELEPHONE. 

up  on  August  6th,  1874,  he  distinctly  put  forward  the  system 
we  have  described,  and  which  is  the  basis  of  those  of  which 
we  have  still  to  speak.  This  specification  was  only  an  addi- 
tion to  two  others  made  out  in  April  and  June,  1874.  Mr. 
Varley's  system  has  only  an  indirect  relation  to  the  one  we 
have  described.  It  appears  from  what  Mr.  Bell  said  on  the 
subject,  in  a  paper  addressed  to  the  Society  of  Telegraphic 
Engineers  in  London,  that  he  himself  only  attaches  a  second- 
ary interest  to  this  invention. 

He  said  that  he  had  been  struck  with  the  idea  that  the 
greater  or  less  duration  of  a  musical  sound  might  represent 
the  dot  and  dash  of  the  telegraphic  alphabet,  and  it  occurred 
to  him  that  simultaneous  telegraphic  transmissions,  of  which 
the  number  should  only  be  limited  by  the  delicacy  of  the 
sense  of  hearing,  might  be  obtained  by  suitable  combinations 
of  long  and  short  sounds,  and  that  these  should  be  effected  by 
a  key-board  of  tuning-forks  applied  to  one  end  of  a  telegraphic 
line,  and  so  arranged  as  to  react  electrically  on  electro -mag- 
netic instruments  striking  on  the  strings  of  a  piano.  For  this 
purpose  it  would  be  necessary  to  assign  an  employe  to  each 
of  the  keys  for  the  service  of  transmission,  and  to  arrange  that 
his  correspondent  should  only  distinguish  his  peculiar  note 
among  all  those  transmitted.  It  was  this  idea,  Mr.  Bell  adds, 
which  led  to  his  researches  in  telephony. 

For  several  years  he  sought  for  the  best  mode  of  reprodu- 
cing musical  sounds  at  a  distance  by  means  of  vibrating  rheo- 
tomes:  the  best  results  were  given  by  a  steel  plate  vibrating 
between  two  contacts,  of  which  the  vibrations  were  electrically 
produced  and  maintained  by  an  electro -magnet  and  a  local 
battery.  In  consequence  of  its  vibration,  the  two  contacts 
were  touched  alternately,  and  the  two  circuits  were  alternately 
broken — the  local  circuit  which  kept  the  plate  in  vibration,  and 
the  other  which  was  connected  with  the  line,  and  reacted  on 
the  distant  receiver,  so  as  to  effect  simultaneous  vibrations  in 


211 

it.  A  Morse  key  was  placed  in  the  latter  circuit  near  the 
sending  instrument,  and  when  it  was  lowered,  vibrations  were 
sent  through  the  line ;  when  it  was  raised,  these  vibrations 
ceased,  and  it  is  easy  to  see  that,  by  lowering  the  key  for  a 
longer  or  shorter  time,  the  short  and  long  sounds  necessary  for 
the  different  combinations  of  telegraphic  language  could  be 
obtained.  Moreover,  if  the  vibrating  plate  of  the  receiving  in 
strument  were  so  regulated  as  to  vibrate  in  unison  with  the 
sending  instrument  in  correspondence,  it  would  vibrate  better 
with  this  sender  than  with  another  whose  plate  was  not  so 
adjusted. 

It  is  evident  that  different  sounds  might  be  simultaneously 
transmitted  with  several  plates  by  this  arrangement  of  con- 
tact breaker,  and  that  at  the  receiving-station  the  sounds  might 
be  distinguished  by  each  employe,  since  the  one  which  corre- 
sponds to  the  fundamental  note  of  each  vibrating  plate  is  re- 
produced by  that  plate.  Consequently,  the  sounds  produced 
by  the  vibrating  plate  of  do,  for  example,  will  only  be  audible 
at  the  receiving-station  on  the  plate  tuned  to  do,  and  the  same 
will  be  the  case  with  the  other  plates ;  so  that  the  sounds  will 
reach  their  destination,  if  not  without  confusion,  yet  with  suffi- 
cient clearness  to  be  distinguished  by  the  employes. 

Mr.  Bell  sums  up  the  defects  still  existing  in  his  system  as 
follows:  1st.  The  receiver  of  the  messages  must  have  a  good 
musical  ear,  in  order  to  distinguish  the  value  of  sounds.  2d. 
Since  the  signals  can  only  take  place  when  the  transmitted  cur- 
rents are  in  the  same  direction,  two  wires  must  be  employed 
in  order  to  exchange  messages  on  each  side. 

He  surmounted  the  first  difficulty  by  providing  the  receiver 
with  an  instrument  which  he  called  the  vibrating  contact 
breaker,  and  which  registered  automatically  the  sounds  pro- 
duced. This  contact  breaker  was  placed  in  the  circuit  of  a 
local  battery,  which  could  work  a  Morse  instrument  under  cer- 
tain conditions.  When  the  sounds  emitted  by  the  instrument 


212  THE   TELEPHONE. 

did  not  correspond  with  those  for  which  it  had  been  tuned, 
the  contact  breaker  had  no  effect  on  the  telegraphic  instru- 
ment: it  only  acted  when  the  sounds  were  those  which  were 
to  be  interpreted,  and  its  action  necessarily  corresponded  to 
the  length  of  the  sounds. 

Mr.  Bell  adds  that  he  applied  the  system  to  electro-chemi- 
cal telegraphs;  but  we  need  not  dwell  on  this  part  of  the  in- 
vention, since,  as  we  have  said,  it  is  no  longer  his  special 
study. 

System  of  M.  Lacour  of  Copenhagen. — M.  Lacour's  system 
was  patented  on  the  2d  September,  1874,  but  his  experiments 
were  commenced  on  the  5th  June  of  the  same  year.  Since  M. 
Lacour  believed  that  the  vibrations  would  be  imperceptible  on 
long  lines,  his  first  attempts  were  made  on  a  somewhat  short 
line;  but  in  November,  1874,  fresh  experiments  were  made 
between  Fredericia  and  Copenhagen  on  a  line  225  miles  in 
length  and,  it  was  ascertained  that  vibratory  effects  could  be 
easily  transmitted,  even  under  the  influence  of  a  rather  weak 
battery. 

In  M.  Lacour's  system  the  sending  instrument  is  a  simple 
tuning-fork,  placed  in  a  horizontal  position,  and  one  of  its  arms 
reacts  on  a  contact  breaker,  which  can  produce  precisely  the 
same  number  of  discharges  of  currents  as  there  are  vibrations 


FIG.  59. 


of  the  tuning-fork.  If  a  Morse  manipulator  is  inserted  in  the 
circuit,  it  is  evident  that  if  it  is  worked  so  as  to  produce  the 
dots  and  dashes  of  the  Morse  alphabet,  the  same  signals  will 
be  reproduced  at  the  opposite  station,  and  the  signals  will  be 


213 

manifested  by  long  and  short  sounds,  if  an  electro  -  magnetic 
receiver  is  connected  with  the  circuit.  This  sender  is  shown 
Fig.  59. 

Fig.  60  represents  M.  Lacour's  receiver.     It  consists  of  a 
tuning-fork,  F,  made  of  soft  iron,  not  of  steel,  like  the  sending 


FIG.  60. 

tuning-fork,  and  each  of  its  branches  is  inserted  in  the  bobbin 
of  an  electro-magnetic  coil,  C  C ;  two  distinct  electro-magnets, 
M  M,  react  close  to  the  extremities  of  the  fork,  in  such  a  way 
that  the  polarities  developed  on  the  two  branches  of  the  fork 
under  the  influence  of  the  coils,  C  C,  should  be  of  contrary 
signs  to  those  of  the  electro-magnets,  M  M. 

If  this  double  electro-magnetic  system  is  inserted  in  a  line 
circuit,  it  follows  that,  for  each  discharge  of  the  transmitted 
current,  a  corresponding  attraction  of  the  branches  of  the  tun- 
ing-fork will  take  place,  and  consequently  there  will  be  a  vibra- 
tion, producing  a  sound,  if  the  discharges  are  numerous.  This 
sound  will  naturally  be  short  or  long  in  proportion  to  the  dura- 
tion of  the  sender's  action,  and  it  will  be  the  same  as  that  of 
the  tuning-fork  in  that  instrument.  Again,  if  one  branch  of 


214  THE    TELEPHONE. 

the  tuning- fork  reacts  on  a  contact,  P,  inserted  in  the  circuit  of 
the  local  battery  communicating  with  a  Morse  receiver,  traces 
will  be  produced  on  this  receiver  of  length  varying  with  the 
duration  of  the  sounds,  for  the  Morse  electro-magnet  will  be  so 
quickly  affected  by  the  successive  breaks  in  the  current  that  its 
armature  will  remain  stationary  throughout  each  vibration.  "  I 
have  not  yet  been  able,"  said  M.  Lacour,  in  an  address  delivered 
before  the  Danish  Academy  of  Science  in  1875,  "to  calculate 
the  time  necessary  for  the  production  of  definite  vibrations  in 
the  tuning-fork.  Different  factors  have  to  be  considered ;  but 
experiment  has  shown  that  the  time  which  elapses  before  the 
local  circuit  is  broken  is  such  a  small  fraction  of  a  second  as 
to  be  almost  inappreciable,  even  when  the  current  is  very  weak. 

"Since  intermittent  currents  only  affect  a  tuning-fork  on 
condition  that  it  vibrates  in  unison  with  the  one  which  pro- 
duces them,  it  follows  that  if  a  series  of  sending  tuning-forks, 
tuned  to  the  different  notes  of  the  scale,  is  placed  at  one  end  of 
a  circuit,  and  if  a  similar  series  of  electro-magnetic  tuning-forks, 
in  exact  accordance  with  the  first,  is  placed  at  the  other  end  of 
the  circuit,  the  intermittent  currents  transmitted  by  the  send- 
ing tuning-forks  will  be  added  to  each  other  without  becoming 
confused,  and  each  of  the  receiving  tuning-forks  will  only  be 
affected  by  the  currents  emitted  by  the  tuning-fork  in  unison 
with  it.  In  this  way  the  combinations  of  elementary  signals 
representing  a  word  may  be  telegraphed  simultaneously." 

M.  Lacour  enumerates  the  ways  in  which  this  system  may 
be  applied  as  follows:  "If  the  keys  in  connection  with  the 
sending  tuning-forks  are  placed  side  by  side,  and  are  lowered 
in  succession,  or  two  or  three  together,  it  will  be  enough  to 
play  on  the  keys  as  on  a  musical  instrument,  in  order  that  the 
air  may  be  heard  at  the  receiving  station,  or  the  signals  trans- 
mitted simultaneously  may  each  belong  to  a  different  message. 
This  system  will  therefore  allow  the  farthest  station  on  a  line 
to  communicate  with  one  or  several  intermediate  stations,  and 


215 

vice  versa,  without  disturbing  the  communication  at  other  sta- 
tions. In  this  way  two  stations  can  exchange  signals  unper- 
ceived  by  the  rest.  The  power  of  sending  many  signals  at 
once  affords  a  good  means  of  improving  the  autographic  tele- 
graph. In  the  instruments  now  in  use,  such  as  those  of  Ca- 
selli  and  D'Arlincourt,  there  is  only  one  tracing  stylus,  and  this 
stylus  must  pass  over  the  whole  surface  of  the  telegram  in  or- 
der to  obtain  a  copy  of  it;  but  with  the  telephone  a  certain 
number  of  styli  may  be  placed  side  by  side  in  the  form  of  a 
comb,  and  this  comb  need  only  be  drawn  in  a  certain  direction 
to  pass  over  the  surface  of  the  telegram.  In  this  way  a  more 
faithful  copy  will  be  obtained  in  a  shorter  time." 

M.  Lacour  also  observes  that  his  system  possesses  a  merit  al- 
ready pointed  out  by  Mr.  Varley,  namely,  that  the  instruments 
permit  the  passage  of  ordinary  currents  without  revealing  their 
presence,  whence  it  follows  that  the  accidental  currents  which 
often  disturb  telegraphic  transmission  will  have  no  effect  on 
these  systems. 

M.  Lacour  began  without  applying  an  electro-magnetic  sys- 
tem to  his  instrument  in  order  to  maintain  the  movement  of 
the  tuning-fork;  but  he  soon  saw  that  this  accessory  was  in- 
dispensable, and  he  made  the  tuning-forks  themselves  electro- 
magnetic. It  also  occurred  to  him  to  convert  the  transmitted 
currents  into  pulsatory  currents  by  inserting  an  induction  coil 
in  the  circuit,  which  was  also  done  by  Mr.  Elisha  Gray.  Final- 
ly, in  order  to  obtain  the  immediate  action  of  the  tuning-forks 
and  the  immediate  cessation  of  their  action,  he  constructed 
them  so  as  to  reduce  their  inertia  as  much  as  possible.  This 
was  effected  by  inserting  the  two  branches  of  the  tuning-fork 
in  the  same  coil  and  by  lengthening  its  handle,  and  turning  it 
back  so  that  it  might  pass  through  a  second  coil,  dividing  into 
two  branches,  and  embracing  the  two  vibrating  branches,  but 
without  touching  them.  When  a  current  traverses  both  coils, 
it  produces,  in  the  kind  of  horseshoe  magnet  formed  by  the 


216 


THE   TELEPHONE. 


two  systems,  opposite  polarities,  which  provoke  a  double  reac- 
tion in  the  vibrating  branches — a  reaction  by  repulsion  exerted 
by  the  two  branches  in  virtue  of  the  same  polarity,  and  a  re- 
action by  attraction  by  the  other  two  branches  in  virtue  of 
their  opposite  polarities ;  and  this  double  action  is  repeated 
by  the  movements  of  a  contact  breaker  applied  to  one  of  the 
vibrating  branches  of  the  tuning-fork. 

Mr.  Elisha  Gray's  System. — According  to  the  system  origi- 
nally patented,  each  sender,  represented  in  Fig.  61,  consists  of  an 
electro-magnet,  M  M,  resting  below  a  small  copper  tablet,  B  S,  in 
such  a  way  that  its  poles  pass  through  this  tablet  and  are  on 
a  level  with  its  upper  surface.  A  steel  plate,  A  S,  is  fixed 
above  these  poles ;  its  tension  can  be  regulated  by  means  of  a 
screw,  S ;  and  another  screw,  c,  is  placed  on  the  plate,  and  is  in 
electric  communication  with  a  local  battery,  R',  by  means  of  a 
Morse  key.  Below  the  plate  A  S  there  is  a  contact,  d,  con- 


.  61. 


nected  with  the  line  wire,  L  ;  this  contact  is  met  by  the  plate 
at  the  moment  of  its  attraction  by  the  electro  -  magnet,  and 
breaks  the  current  of  a  line  battery,  P,  which  acts  on  the  re- 
ceiver of  the  opposite  station.  Finally,  the  electric  communi- 
cation established  between  the  local  battery  R'  and  the  electro- 
magnet, as  may  be  seen  in  the  figure,  produces  vibrations  in 
the  steel  plate  A  S  at  each  lowering  of  the  key,  as  in  the  case 
of  ordinary  vibrations  —  vibrations  which,  with  a  suitable  ten- 
sion of  the  plate  and  a  given  intensity  of  the  battery  R',  can 


GRAY'S  SYSTEM. 


217 


produce  a  definite  musical  note.  Moreover,  since  at  eacli  vibra- 
tion the  plate  A  S  meets  the  contact,  discharges  of  the  line 
current  take  place  through  the  line  L,  and  react  on  the  receiv- 
ing instrument,  causing  it  to  reproduce  exactly  the  same  vibra- 
tions as  those  of  the  sending  instrument. 

The  receiving  instrument  represented  in  Fig.  62  exactly  re- 
sembles the  one  we  have  just  described,  except  that  there  is  no 


FIG.  02. 

contact,  d,  below  the  vibrating  plate  A  S,  and  the  contact  c,  in- 
stead of  communicating  with  the  line  wire,  is  in  electric  con- 
nection with  a  register,  E,  and  a  local  battery,  P.  It  follows 
from  this  arrangement  that  when  the  plate  A  S  vibrates  under 
the  influence  of  the  broken  currents  passing  through  the  elec- 
tro-magnet M  M,  similar  vibrations  are  sent  through  the  regis- 
ter ;  but  if  the  electro-magnetic  organ  of  this  register  is  prop- 
erly regulated,  these  vibrations  can  only  produce  the  effect  of 
a  continuous  current,  and  hence  the  length  of  the  traces  left 
on  the  instrument  will  vary  with  the  duration  of  the  sounds 
produced.  In  this  way  the  registration  of  the  dashes  and  dots 
which  constitute  the  signs  of  the  Morse  vocabulary  will  be 
effected. 

If  it  is  remembered  that  the  plate  A  S  vibrates  under  the 
influence  of  electro-magnetic  attractions  more  readily  in  pro- 
portion to  their  approximation  in  number  to  the  vibrations 
corresponding  to  the  fundamental  sound  it  can  emit,  it  be- 
comes clear  that  if  this  plate  is  tuned  to  the  same  note  as  that 

10 


218  THE.  TELEPHONE. 

of  the  corresponding  instrument,  it  will  be  rendered  peculiar- 
ly sensitive  to  the  vibrations  transmitted  by  the  sender,  and 
the  other  vibrations  which  may  affect  it  will  only  act  faintly. 
Moreover,  a  resonator  placed  above  the  plate  will  greatly  in- 
crease this  predisposition;  so  that  if  several  systems  of  this 
kind,  tuned  to  different  notes,  produce  simultaneous  transmis- 
sions, the  sounds  corresponding  to  the  different  vibrations 
will  be  in  a  certain  sense  selected  and  distributed,  in  spite  of 
their  combination,  into  the  receivers  for  which  they  are  spe- 
cially adapted,  and  each  of  them  may  retain  the  traces  of  the 
sounds  emitted  by  adding  the  register,  which  may  be  so  ar- 
ranged as  to  act  as  an  ordinary  Morse  receiver.  Mr.  Gray 
states  that  the  number  of  sending  instruments  and  indepen- 
dent local  circuits  may  be  equal  to  that  of  the  tones  and  semi- 
tones of  two  or  more  octaves,  provided  that  each  vibrating 
plate  be  tuned  to  a  different  note  of  the  scale.  The  instru- 
ments may  be  placed  side  by  side,  and  their  respective  local 
keys,  arranged  like  the  keys  of  a  piano,  will  make  it  easy  to 
play  an  air  combining  notes  and  chords  ;  there  may  also  be  an 
interval  between  the  instruments,  which  may  be  sufficiently  far 
from  each  other  to  allow  the  employes  to  work  without  being 
distracted  by  sounds  not  intended  for  them. 

In  a  nQVf  arrangement,  exhibited  at  the  Paris  Exhibition, 
1878,  Mr.  Gray  considerably  modified  the  way  of  working  the 
various  electro-magnetic  organs  which  we  have  just  described. 
In  this  case,  the  plates  consist  of  tuning-forks  with  one  branch 
kept  in  continual  vibration  at  both  stations,  and  the  signals 
only  become  perceptible  by  intensifying  the  sounds  produced. 
This  arrangement  follows  from  the  necessity  of  keeping  the 
line  circuit  always  closed  for  multiple  transmissions  of  this 
nature,  so  as  to  react  with  pulsatory  currents,  which  are  alone 
able,  as  we  have  already  seen,  to  retain  the  individual  character 
of  several  sounds  simultaneously  transmitted. 

Under    these    conditions   the   sender    consists,   as   we    see 


GRAY  S   SYSTEM. 


219 


(Fig.  63),  of  a  bar  tuning-fork,  a,  which  is  grooved  for  the 
passage  of  a  runner,  heavy  enough  to  tune  the  fork  to  the 
desired  note,  and  it  oscillates  between  two  electro-magnets,  e 


B^L 


Earth 


FIG.  63. 

and  /,  and  two  contacts,  I  and  G.  The  difference  of  resistance 
in  the  electro-magnets  is  very  great :  in  the  one,/,  the  resist- 
ance is  equal  to  two  and  three-quarter  miles  of  telegraphic 
wire,  in  the  other  it  does  not  exceed  440  yards.  When  elec- 
tric communication  is  established,  as  we  see  in  the  figure,  the 
following  effect  takes  place:  Since  the  current  of  the  local 
battery  through  the  two  electro-magnets  is  broken  by  the  rest- 
contact  of  the  Morse  key  H,  the  plate  a  is  subject  to  two  con- 
trary actions ;  but  since  the  electro-magnet  /  has  more  turns 
than  the  electro-magnet  e,  its  action  is  preponderant,  and  the 
plate  is  attracted  toward  f,  and  produces  a  contact  with  the 
spring  G,  which  opens  a  way  of  less  resistance  for  the  current. 


220 


THE   TELEPHONE. 


Since  the  current  then  passes  almost  wholly  through  G,  ft,  1, 
2,  B,  the  electro-magnet  is  now  able  to  act ;  the  plate  a  is  then 
attracted  toward  e,  and,  by  producing  a  contact  on  the  spring 
I,  it  sends  the  current  of  the  line  B  P  through  the  telegraphic 
line,  if  the  key  II  is  at  the  same  time  lowered  on  the  sending 
contact :  if  not,  there  will  be  no  effect  in  this  direction ;  but 
since  the  plate  a  has  left  the  spring  G,  the  first  effect  of  attrac- 
tion by  the  electro-magnet/will  be  repeated,  and  this  tends 
to  draw  the  plate  again  toward/.  This  state  of  things  is  re- 
peated indefinitely,  so  as  to  maintain  the  vibration  of  the  plate, 
and  to  send  out  signals  corresponding  with  these  vibrations 
whenever  the  key  II  is  lowered.  The  elastic  nature  of  the 
plate  makes  these  vibrations  more  easy,  and  it  ought  also  to 
be  put  in  mechanical  vibration  at  the  outset. 

The  receiver,  represented  in  Fig.  64,  consists  of  an  electro- 


FIG.  04. 


magnet,  M,  mounted  on  a  sounding -box,  C,  and  having  an 
armature  formed  by  a  tuning-fork,  L  L,  firmly  buttressed  on 
the  box  by  a  cross-bar,  T.  There  is  a  runner,  P,  on  the  arma- 


221 

ture,  sliding  in  a  groove,  which  makes  it  possible  to  tune  the 
vibrations  of  the  tuning-fork  to  the  fundamental  note  of  the 
sounding-box  C,  which  is  so  arranged  as  to  vibrate  in  unison 
with  it.  Under  these  conditions  the  box  as  well  as  the  tun- 
ing-fork will  act  as  an  analyzer  of  the  vibrations  transmitted 
by  the  currents,  and  may  set  the  register  at  work  by  itself 
reacting  on  a  breaker  of  the  local  current.  To  obtain  this  re- 
sult, a  membrane  of  gold-beater's  skin  or  parchment  must  be 
stretched  before  the  opening  of  the  box,  and  a  platinum  con- 
tact must  be  applied  to  it,  so  arranged  as  to  meet  a  metallic 
spring  connected  with  any  kind  of  register  or  a  Morse  instru- 
ment, when  the  membrane  vibrates.  As,  however,  in  America 
the  messages  are  generally  received  by  sound,  this  addition  to 
the  system  is  not  in  use. 

The  instrument  is  not  only  regulated  by  the  runner  P,  but 
also  by  a  regulating  screw,  Y,  which  allows  the  electro-magnet 
M  to  be  properly  adjusted.  The  regulating  system  is  made 
more  exact  by  the  small  screw,  V,  and  the  instrument  is  con- 
nected with  the  line  by  the  binding-screw,  B.  Of  course  this 
double  arrangement  is  necessary  for  each  of  the  sending  sys- 
tems. 

As  I  have  already  said,  seven  different  messages  might  theo- 
retically be  sent  at  once  in  this  way,  but  Mr.  Gray  has  only 
adapted  his  instrument  for  four ;  he  has,  however,  made  use  of 
the  duplex  system,  which  allows  him  to  double  the  number  of 
transmissions,  so  that  eight  messages  may  be  sent  at  the  same 
time — four  in  one  direction,  and  four  in  another. 

Mr.  Hoskins  asserts  that  this  system  has  been  worked  with 
complete  success  on  the  lines  of  the  Western  Union  Telegraph 
Company,  from  Boston  to  New  York,  and  from  Chicago  to 
Milwaukee.  Since  these  experiments  were  made,  fresh  im- 
provements have  rendered  it  possible  to  send  a  much  larger 
number  of  messages. 

Mr.  Gray  has  also,  aided  by  Mr.  Hoskins,  devised  a  system 


222  THE    TELEPHONE. 

by  which  telephonic  messages  may  be  sent  on  a  wire  previous- 
ly used  for  Morse  instruments.  Mr.  Varley  had  already  solved 
this  problem,  but  Mr.  Gray's  system  seems  to  have  produced 
important  results,  and  has  therefore  a  claim  to  our  attention. 
We  do  not,  however,  describe  it  here,  since  it  is  not  within  the 
lines  marked  out  for  us,  and  those  who  are  interested  in  the 
subject  will  find  all  the  necessary  details  in  a  paper  inserted  in 
the  Journal  of  the  Society  of  Telegraphic  Engineers,  London, 
vol.  vi. 

Mr.  Var ley's  System. — This  system  is  evidently  the  earliest 
in  date,  since  it  was  patented  in  1870,  and  the  patent  describes 
the  principle  of  most  of  the  arrangements  which  have  since 
been  adopted  by  Messrs.  Lacour,  Gray,  and  Bell.  It  is  based 
upon  the  use  of  his  own  musical  telephone,  which  we  have  al- 
ready described,  but  with  some  variations  in  its  arrangement, 
which  make  it  somewhat  like  the  Reiss  system. 

It  was  Mr.  Varley's  aim  to  make  his  telephone  work  in  con- 
junction with  instruments  with  ordinary  currents,  by  the  addi- 
tion of  rapid  electric  waves,  incapable  of  making  any  practical 
change  in  the  mechanical  or  chemical  capacity  of  the  currents 
which  serve  for  the  ordinary  signals,  yet  able  to  make  distinct 
signals,  perceptible  to  the  ear  and  even  to  the  eye.  He  says : 
"An  electro-magnet  offers  at  first  a  great  resistance  to  the  pas- 
sage of  an  electric  current,  and  may  consequently  be  regarded 
as  a  partially  opaque  body  with  respect  to  the  transmission  of 
very  rapid  inverse  currents  or  of  electric  waves.  Therefore,  if 
a  tuning-fork,  or  an  instrument  with  a  vibrating  plate,  tuned  to 
a  given  note,  be  placed  at  the  sending  station,  and  so  arranged 
as  to  be  kept  in  constant  vibration  by  magnetic  influence,  the 
current  which  acts  upon  it  must  be  passed  into,  two  helices 
placed  one  above  the  other,  so  as  to  constitute  the  primary 
helix  of  an  induction  coil ;  in  this  way  it  will  be  possible  to 
obtain  in  two  distinct  circuits  two  series  of  rapidly  broken  cur- 
rents, which  will  correspond  to  the  two  directions  of  the  vibra- 


223 

tions  of  the  tuning-fork,  and  we  shall  also  have  the  induced 
currents  produced  in  the  secondary  helix  by  these  currents, 
•which  may  act  on  a  third  circuit.  This  third  circuit  may  be 
placed  in  connection  with  a  telegraphic  line  previously  used  by 
an  ordinary  telegraphic  system,  if  a  condenser  is  applied  to  it, 
and  in  this  way  two  different  transmissions  may  be  obtained 
simultaneously." 

Fig.  65  represents  the  arrangement  of  this  system.     D  is  the 


vibrating  plate  of  the  tuning-fork  designed  to  produce  the  elec- 
tric contacts  necessary  to  maintain  it  in  motion.  These  con- 
tacts are  at  S  and  S',  and  the  electro-magnets  which  affect  it 
are  at  M  and  M'.  The  induction  coil  is  at  I',  and  the  three 
helices  of  which  it  is  composed  are  indicated  by  the  circular 
lines  which  surround  it.  There  is  a  Morse  manipulator  at  A, 
another  at  A',  and  the  two  batteries  which  work  the  system  are 
at  P  and  P'.  The  condenser  is  at  C,  and  the  telephone  is  at 
the  end  of  the  line  L. 

AVhen  the  vibration  of  the  plate  D  tends  to  the  right,  and 
the  electric  contact  takes  place  at  S',  the  current  of  the  battery 
P',  after  traversing  the  primary  helix,  reaches  the  electro-mag- 
nets M  M',  which  give  it  an  impulse  in  the  contrary  direction. 
AVhen,  on  the  other  hand,  it  tends  to  the  left,  the  current  is 
sent  through  the  second  primary  circuit,  which  will  be  balanced 
by  the  first.  Consequently  there  will  be  a  series  of  reversed 
currents  in  the  induced  circuit  corresponding  to  the  key  A', 
which  will  alternately  charge  and  discharge  the  condenser  C, 


224  THE   TELEPHONE. 

thus  sending  into  the  line  a  corresponding  series  of  electric  un- 
dulations, which  will  react  on  the  telephone  placed  at  the  end 
of  the  line ;  and  as  the  duration  of  the  transmitted  currents 
will  vary  with  the  time  that  the  key  A'  is  lowered,  a  corre- 
spondence in  the  Morse  code  may  be  obtained  in  the  telephone, 
while  another  correspondence  is  exchanged  with  the  key  A  and 
the  ordinary  Morse  receivers. 

In  order  to  render  the  vibratory  signals  visible,  Mr.  Varley 
proposes  to  use  a  fine  steel  wire,  stretched  through  a  helix  and 
facing  a  narrow  slit,  to  reproduce  the  vibrations.  A  light, 
which  is  intercepted  by  the  wire,  is  placed  behind  the  slit. 
As  soon  as  a  current  passes,  the  wire  vibrates  and  the  light 
appears.  A  lens  is  placed  so  as  to  magnify  the  image  of  the 
luminous  slit,  and  project  it  on  a  white  screen  while  the  wire  is 
in  vibration. 

VARIOUS  USES  OF  THE  TELEPHONE. 

Its  Domestic  Application. — We  have  seen  that  telephones 
may  be  used  with  advantage  in  public  and  private  offices  :  they 
can  be  set  up  at  a  much  less  expense  than  acoustic  tubes,  and 
in  cases  where  the  latter  would  never  be  employed.  With  the 
aid  of  the  calls  we  have  described,  they  offer  the  same  advan- 
tages, and  the  connection  between  the  instruments  is  more 
easily  concealed.  The  difference  of  price  in  establishing  them 
is  in  the  ratio  of  one  to  seven. 

For  this  purpose  electro-magnetic  telephones  are  evidently 
the  best,  since  they  require  no  battery,  and  are  always  ready  to 
work.  They  are  already  in  use  in  many  government  offices, 
and  it  is  probable  that  they  will  soon  be  combined  with  elec- 
tric bells  for  the  service  of  hotels  and  of  large  public  and  private 
establishments ;  they  may  even  be  used  in  private  houses  for 
giving  orders  to  servants  and  porters,  who  may  thus  save  visi- 
tors from  the  fatigue  of  a  useless  ascent  of  several  stories. 

In  factories,  telephones  will  certainly  soon  replace  the  tele- 


ITS   APPLICATIOX  TO   THE   TELEGKAPII.  225 

graphic  communication  which  has  already  become  general. 
They  may  not  only  be  used  for  ordinary  messages,  but  to  call 
for  help  in  case  of  fire,  and  they  will  become  an  integral  part 
of  several  systems  already  established  for  this  purpose. 

In  countries  which  have  free  telegraphic  communication,  the 
telephone  has  already  replaced,  in  great  measure,  the  private 
telegraph  instruments  which  have  hitherto  been  in  use ;  and  if 
the  same  privilege  is  extended  to  France,  no  other  mode  of  cor- 
respondence will  be  used. 

Its  Application  to  Telegraphic  Service. — The  advantage  to 
be  derived  by  the  telegraphic  service  from  the  telephone  is 
rather  limited,  since,  as  far  as  the  speed  of  transmission  is  con- 
cerned, it  is  of  less  value  than  many  of  the  telegraphic  instru- 
ments now  in  use,  and  the  messages  which  it  produces  cannot 
be  registered.  Yet  in  municipal  offices  not  overburdened  with 
messages  they  offer  the  advantage  of  not  requiring  a  trained 
service.  On  longer  lines  their  use  would  be  of  little  value. 
The  Berne  Telegraphic  Journal  has  published  some  interesting 
remarks  on  this  subject,  of  which  the  following  is  a  summary : 

1st.  In  order  to  send  a  message  with  the  special  advantages 
of  the  system,  the  sender  ought  to  be  able  to  address  his  corre- 
spondent without  the  intervention  of  an  official.  Those  who 
are  acquainted  with  the  network  of  wires  know  this  to  be  im- 
possible. Intermediate  offices  for  receiving  messages  are  essen- 
tial, and  the  public  cannot  be  admitted  to  those  set  apart  for 
sending  and  receiving,  consequently  the  sender  must  deliver  a 
written  message. 

2d.  If  the  message  is  written,  the  chief  advantage  of  the  in- 
strument is  lost,  since  it  must  be  read  and  uttered  aloud,  which 
could  not  be  done  if  expressed  in  a  language  with  which  the 
employes  were  unacquainted. 

3d.  The  instruments  now  in  use  at  the  telegraph-offices  can 
transmit  messages  more  quickly  than  if  they  were  spoken. 

In  Germany,  however,  a  telephone  service  has  been  establish- 

10* 


226  THE   TELEPHONE. 

ed  in  several  telegraph-offices,  and  its  possible  advantages  are 
enumerated  as  follows  in  the  official  circular  which  created  it : 

"  The  offices  which  will  be  opened  to  the  public  for  the  ser- 
vice of  telephonic  messages  in  Germany  will  be  regarded  as  in- 
dependent establishments ;  yet  they  will  be  in  connection  with 
the  ordinary  telegraph  -  offices,  which  will  undertake  to  send 
telephonic  messages  through  their  wires. 

"The  transmission  will  take  place  as  follows:  The  sending- 
office  will  request  the  receiving-office  to  prepare«the  instrument ; 
as  soon  as  the  tubes  are  adjusted,  the  sending-office  will  give 
the  signal  for  despatching  the  verbal  message. 

"  The  sender  must  speak  slowly  and  clearly,  without  raising 
his  voice ;  each  syllable  must  be  distinctly  pronounced ;  the 
final  syllables  especially  must  be  well  articulated,  and  there 
must  be  a  pause  after  each  word,  in  order  to  give  the  receiver 
time  to  write  it  down. 

"  When  the  telegram  has  been  received,  the  employe  at  the 
receiving  -  office  must  verify  the  number  of  words;  then  he 
must  repeat  through  the  telephone  the  whole  message  without 
pausing,  so  as  to  make  sure  that  there  is  no  mistake. 

"  In  order  to  insure  secrecy,  the  telephones  are  placed  apart, 
where  persons  unconnected '  with  the  service  cannot  hear  the 
verbal  message,  and  the  employes  are  forbidden  to  reveal  to 
any  one  the  names  of  the  correspondents. 

"The  charge  for  telephonic  messages,  as  for  the  ordinary 
telegraphic  services,  is  at  the  rate  of  so  much  a  word." 

The  use  of  the  telephone  has  also  been  suggested  for  verify- 
ing the  perfect  junction  of  telegraphic  wires.  It  is  certain  that, 
if  the  junction  is  complete,  no  abnormal  sounds  will  be  heard, 
or  only  those  which  result  from  accidental  currents ;  but  if  the 
junction  is  bad,  the  imperfect  contacts  which  take  place  pro- 
duce variations  in  electric  intensity  which  are  translated  into 
the  more  or  less  marked  sounds  observed  in  the  telephone. 

M.  Mauborgne,  the  electrician  attached  to  the  Northern  Rail- 


ITS   APPLICATION   TO   THE    ARMY.  227 

way  of  France,  has  lately  used  the  telephone  instead  of  the 
galvanometer  to  ascertain  the  condition  of  the  circuits  in  cor- 
respondence with  the  instruments  in~use  for  electric  signals. 
The  reactions  produced  on  the  galvanometer  needle  by  the 
pieces  of  iron  which  are  placed  at  the  sides  of  the  railway  often 
make  its  indications  uncertain,  and  a  strong  wind  produces 
irregular  movements  in  the  instrument  which  interfere  with 
observations.  It  was  also  necessary  to  place  the  galvanometer 
with  due  regard*  to  the  points  of  the  compass,  and  to  wait  for 
the  needle  to  settle,  which  involved  loss  of  time.  The  opera- 
tion is  easily  accomplished  with  the  telephone,  since  the  strokes 
of  the  call-bell  are  distinctly  reproduced ;  it  is  made  to  ring 
by  working  the  contacts  which  need  verification,  and  in  the 
same  way  the  condition  of  the  battery  can  be  ascertained. 

Application  to  Military  Purposes. — Since  the  telephone  was 
invented,  numerous  experiments  have  been  made  in  different 
countries  to  ascertain  whether  it  would  be  of  use  in  military 
operations.  These  experiments  have  hitherto  been  only  mod- 
erately satisfactory,  on  account  of  the  noise  inseparable  from 
an  army,  which  generally  makes  it  impossible  to  hear  the  tele- 
phone, and  every  means  of  intensifying  its  sounds  has  been 
eagerly  sought.  It  was  at  first  supposed  that  the  discovery  of 
the  microphone  had  solved  the  problem,  and  I  received  many 
inquiries  from  military  schools  on  the  subject,  but  I  have  not 
been  able  to  see  that  anything  has  been  gained  from  this  point 
of  view.  The  telephone  is,  however,  of  great  use  in  schools  of 
artillery  and  rifle  practice.  Now  that  fire-arms  carry  so  far,  it 
has  become  necessary  to  be  informed  by  telegraph  of  the  points 
hit  on  the  target,  in  order  to  judge  of  the  accuracy  of  aim,  and 
for  this  purpose  telegraphic  targets  were  suggested ;  but  tele- 
phones are  much  to  be  preferred,  and  they  are  now  used  with 
good  effect. 

If  the  telephone  is  unsuited  for  the  service  of  the  flying  tel- 
egraph in  the  field,  it  may  be  of  great  use,  in  the  defence  of 


228  THE    TELEPHONE. 

towns,  to  transmit  the  orders  of  the  commandant  to  different 
batteries,  and  even  for  the  exchange  of  correspondence  with 
captive  balloons  sent  to  hover  over  fields  of  battle. 

In  spite  of  the  difficulties  attending  its  use,  the  experiment 
was  made  by  the  Russians  in  the  late  war;  the  cable  wire  of 
communication  was  500  or  600  yards  long,  and  so  light  that  it 
could  be  laid  by  one  man.  The  Telegraphic  Journal  of  March 
15th,  1878,  states  that  the  bad  weather  did  not  interfere  with 
the  working  of  the  instruments ;  but  the  noise  made  it  difficult 
to  hear,  and  it  was  necessary  to  cover  the  head  with  a  hood  to 
intercept  external  sounds.  This  cannot  be  considered  a  satis- 
factory result,  yet  the  telephone  may  be  of  great  service  to  an 
army  by  intercepting  the  enemy's  messages  :  a  bold  man  pro- 
Tided  with  a  pocket  telephone,  who  placed  himself  in  a  retired 
spot,  might  divert  the  current  of  the  enemy's  telegraphic  wire 
into  his  telephone,  and  get  possession  of  all  his  despatches, 
as  we  saw  was  the  case  at  Clermont.  He  might  even  do 
this  by  diverting  the  current  to  earth  or  to  a  rail  of  the 
railway  line.  These  are  suggestions  for  future  research,  and 
it  is  probable  that  they  may  some  day  be  turned  to  practical 
account. 

Its  Application  to  the  Navy. — The  telephone  may  be  of  the 
greatest  use  in  naval  matters,  for  the  service  of  electro-sema- 
phores, for  island  forts,  and  ships  at  anchor.  M.  Pollard  says 
that  "  experiments  made  between  the  Prefecture  Maritime  at 
Cherbourg,  the  semaphores  and  the  forts  on  the^mole,  demon- 
strate the  advantage  there  would  be  in  establishing  telephones 
at  these  stations,  since  they  would  insure  an  easy  communica- 
tion between  the  vessels  of  a  squadron  and  the  land  they  are 
approaching.  By  sinking  small  cables  which  come  to  the  sur- 
face of  the  water  along  mooring-chains,  and  terminate  in  buoys 
or  cases  which  remain  permanently  in  the  harbor,  the  ships  of 
war  may  in  this  way  place  themselves  in  communication  with 
the  Prefecture  Maritime  as  they  cast  anchor,  and,  by  tempo- 


ITS   APPLICATION   TO   THE    NAVY.  229 

rarily  connecting  the  vessels  together  with  light  cables,  the 
admiral  may  communicate  freely  with  the  whole  squadron." 

The  telephone  has  been  tried  on  board  ship  for  transmitting 
orders,  but  without  success,  on  account  of  the  noise  always 
going  on  in  a  vessel. 

The  telephone  may  be  usefully  applied  to  the  service  of  sub- 
marine torpedoes.  We  have  already  seen  how  it  may  be  ap- 
plied in  connection  with  the  microphone,  but  it  may  also  be 
used  in  firing  the  torpedoes  after  the  exact  position  of  the  ene- 
my's ship  has  been  ascertained  from  two  reconnaissances  taken 
from  different  parts  of  the  coast. 

The  telephone,  again,  makes  it  possible  to  verify  the  condi- 
tion of  torpedoes,  and  to  ascertain  if  there  is  any  fault  in  the 
circuit  within  the  explosives.  For  this  purpose  a  very  weak 
current  has  been  used,  and  a  galvanometer  is  not  always  able 
to  indicate  the  fault,  while  the  extreme  sensitiveness  of  the 
telephone  will  do  so  in  the  simplest  way. 

Captain  M'Evoy,  of  the  American  army,  suggested  a  way  of 
ascertaining,  while  on  shore,  the  condition  of  torpedoes  under 
water,  by  connecting  the  buoys  which  support  them  with  the 
land  by  means  of  a  telephonic  line.  By  inserting,  in  the  buoy 
which  supports  the  torpedo,  metallic  disks,  so  arranged  as  to 
vibrate  with  every  movement  caused  by  the  waves  upon  the 
buoy,  a  continuous  noise  will  be  heard  in  the  telephone,  after 
the  circuit  has  been  completed  by  the  metallic  disks ;  and  the 
noise  will  go  on  as  long  as  the  disks  continue  to  oscillate,  and 
will  cease  as  soon  as  the  buoy  is  completely  covered  by  the 
water.  When  it  ceases,  therefore,  if  not  affected  by  some 
accidental  cause,  it  may  be  supposed  that  the  enemy's  ship  is 
passing  over  the  buoy. 

M.  Treve,  again,  has  shown  that  the  telephone  might  be  used 
with  advantage  for  the  telegraphic  communication  between 
vessels  in  tow,  and  M.  des  Fortes  has  applied  it  with  good 
effect  to  diving  operations.  In  this  instance,  one  of  the  glass 


230  THE   TELEPHONE. 

panes  in  the  helmet  is  replaced  by  a  copper  plate  in  which  the 
telephone  is  framed,  so  that  the  diver  need  only  make  a  slight 
movement  of  his  head  in  order  to  receive  or  address  communi- 
cations to  those  in  charge  of  the  apparatus.  With  this  system 
the  keels  of  vessels  may  be  examined,  and  an  account  given 
of  their  condition,  without  bringing  up  the  divers,  which  has 
hitherto  been  necessary. 

M.  de  Parville,  the  able  and  learned  editor  of  the  Journal 
Scientifique  and  the  science  department  of  the  Journal  des 
Debats,  has  suggested  a  new  and  interesting  application  of  the 
telephone.  It  concerns  the  possibility  of  making  use  of  it  to 
determine  the  precise  position  of  the  magnetic  meridian ;  that 
is,  the  true  direction  of  the  magnetized  needle. 

For  this  purpose  a  Bell  telephone  is  necessary,  of  which  the 
magnetic  core  is  formed  of  an  iron  rod  a  metre  in  length,  kept, 
by  a  suitable  suspension,  at  nearly  the  same  angle  of  inclina- 
tion as  a  dipping-needle.  This  rod  will  be  magnetized  under 
the  influence  of  terrestrial  magnetism,  and  the  telephone  will 
be  able  to  transmit  the  sounds  produced  by  some  sort  of  vibra- 
tor placed  near  its  mouth-piece.  These  sounds  will  be  strong 
in  proportion  to  the  degree  of  magnetization  of  the  bar;  and 
if  the  telephone  is  turned  round  the  horizon,  keeping  the  bar 
at  the  same  angle  of  inclination,  the  sounds  transmitted  to  the 
receiving  telephone  will  be  greatest  when  the  axis  of  the  bar  is 
in  the  plane  of  the  magnetic  meridian,  and  least  when  it  is  at 
90°.  It  will,  therefore,  be  possible  to  ascertain  from  the  direc- 
tion of  the  axis  at  the  moment  when  the  sounds  are  no  longer 
heard  the  exact  inclination  of  the  magnetic  needle  from  north 
to  south,  for  it  will  be  given  by  the  perpendicular  to  the  line 
which  is  followed  by  the  axis  of  the  iron  bar  at  that  moment. 

It  is  possible  that,  with  this  system,  the  disturbing  influence 
on  the  magnetic  needle  of  the  mass  of  iron  in  iron-plated  ves- 
sels might  be  almost  destroyed,  and  a  more  exact  orientation 
than  that  of  the  compass  might  be  obtained.  The  same  proc- 


ITS    APPLICATION   TO    INDUSTRY    AND    SCIENCE.         231 

ess  may  make  it  possible  to  estimate  and  measure  the  varia- 
tions of  terrestrial  magnetism.  M.  de  Parville  has  not  himself 
tried  to  apply  this  system,  but  Mr.  Blake's  experiments,  of  which 
we  spoke  in  an  early  part  of  this  work,  make  it  probable  that 
it  might  be  done  with  advantage. 

Application  to  Industry. — One  of  the  earliest  and  most  im- 
portant applications  of  the  telephone  is  that  which  was  first 
made  to  the  service  of  mines  in  England  and  America  in  the 
autumn  of  1877.  The  great  length  of  the  galleries  is  well 
known,  and  had  already  involved  the  use  of  the  electric  tele- 
graph for  transmitting  orders ;  but  the  miners  did  not  under- 
stand how  to  work  these  instruments,  and  the  service  was  ill 
performed.  Thanks  to  the  telephone,  through  which  the  first 
comer  can  send  and  receive  a  message,  there  is  no  longer  any 
difficulty  in  the  communication  between  the  galleries  and  the 
surface  of  the  mine. 

The  ventilation  of  mines  can  also  be  regulated  by  the  aid  of 
telephones.  If  one  of  these  instruments  is  placed  near  a  wheel 
kept  in  motion  by  the  air  which  passes  through  the  ventilating 
shaft,  and  another  is  placed  in  the  inspector's  office,  he  can  as- 
certain by  the  sound  if  the  ventilation  is  duly  carried  on,  and 
if  the  machine  works  regularly. 

Application  to  Scientific  Research. — M.  d' Arson vaFs  experi- 
ments, which  we  have  already  mentioned,  show  that  the  tele- 
phone can  be  used  as  an  extremely  sensitive  galvanoscope ;  but 
since  it  can  only  produce  sounds  under  the  influence  of  broken 
currents,  the  circuit  on  which  the  experiment  is  made  must  be 
divided  at  rather  close  intervals.  It  has-been  seen  that" it  is 
not  even  necessary  to  insert  the  telephone  in  the  circuit:  it 
may  be  influenced,  when  at  a  distance,  either  immediately  or 
by  the  induction  of  the  broken  current  on  a  circuit  placed  par- 
allel to  the  first,  and  the  force  of  these  effects  may  be  increased 
by  the  reaction  of  a  core  of  iron,  round  which  the  inducing  cir- 
cuit is  wound.  The  drawback  to  this  system  is  that  the  direc- 


232  THE   TELEPHONE. 

tion  of  the  current  is  not  ascertained,  so  that  it  cannot  be  used 
as  a  measuring  instrument ;  but,  on  the  other  hand,  it  is  so  sen- 
sitive, so  easy  to  arrange,  and  so  inexpensive,  that  it  might  be 
of  the  greatest  use  as  a  galvanoscope. 

Mr.  Warren  de  la  Rue  has  also  made  use  of  the  telephone  in 
his  researches  into  the  electric  discharges  of  high-tension  bat- 
teries, in  order  to  follow  the  different  phases  of  the  discharge 
during  the  luminous  phenomena  which  it  produces.  In  this 
way  he  ascertained  that  when  a  condenser  is  placed  in  connec- 
tion with  a  battery  formed  of  a  considerable  number  of  insu- 
lated elements,  and  is  gradually  discharged  through  a  Geissler 
tube,  a  dull  and  faint  sound  is  heard  in  the  telephone,  as  long 
as  the  stratifications  of  light  appear  to  be  perfectly  stable ;  but 
the  sound  becomes  considerably  stronger,  and  sometimes  even 
piercing,  in  proportion  to  the  diffusion  of  these  stratifications, 
and  to  their  approach  to  the  point  of  extinction :  whence  it 
is  shown  that  the  discharge  of  a  battery  into  tubes  in  which  a 
vacuum  has  been  made  is  intermittent. 

Mr.  Spottiswoode  has  repeated  the  same  experiments  with 
the  discharges  of  Holtz  machines,  and  with  large  condensers, 
and  he  found  that  the  most  piercing  sounds  produced  by  the 
telephone  coincided  with  the  greatest  development  of  the  strati- 
fications. These  sounds,  however,  sometimes  ceased  for  a  mo- 
ment. It  was  even  possible  to  ascertain,  from  the  intensity  of 
the  sounds  produced,  the  differences  of  tension  which  might  be 
manifested  in  the  charge  of  the  condenser  and  the  slackening 
of  the  machine's  motion,  and  the  differences  of  intensity  in 
these  sounds  might  in  some  cases  exceed  an  octave.  The  fall 
in  the  scale  generally  appeared  in  half-tones  instead  of  gradu- 
ally, and  the  introduction  of  resistances  into  the  circuit  modi- 
fied the  sounds  very  much :  they  might  even  be  intensified  by 
approaching  the  finger  to  the  discharging  tube. 

From  experiments  made  with  the  telephone  between  Calais 
and  Boulogne,  it  appears  that  this  instrument  might  be  ap- 


ITS    USE    IN   ARTILLERY   PRACTICE.  233 

plied  with  advantage  to  the  science  of  projectiles.  In  fact,  in 
some  artillery  practice  which  took  place  on  the  shore  at  Bou- 
logne, a  telephone  was  placed  close  to  the  gun,  and  the  explo- 
sion was  heard  at  a  distance  of  nearly  two  miles,  where  the 
projectile  fell.  It  was  possible  to  estimate  its  velocity  by 
measuring  the  lapse  of  time  between  the  moment  when  the 
projectile  left  the  gun,  and  its  fall.  This  calculation  is  usually 
made  by  observing  the  flash  from  the  cannon's  mouth ;  but  in 
some  cases,  as  in  a  fog  or  in  practice  at  long  ranges,  the  tele- 
phone may  be  usefully  substituted  for  ocular  observation.  On 
the  field  of  battle,  an  observer,  provided  with  a  telephone  and 
placed  on  a  hill,  might  rectify  from  a  distance  the  aim  of  his 
battery,  which  is  generally  established  in  a  sheltered  and  less 
elevated  place. 


L  I  P>  K  A  It  V 

UNIVKKSITY   <) 

(^CALIFORNIA 

THE  PHONOGRAPH. 


MR.  EDISON'S  Phonograph,,  which  has  for  ike  last  year  at- 
tracted so  much  attention,  is  an  instrument  which  not  only 
registers  the  different  vibrations  produced  by  speech  on  a 
vibrating  plate,  but  reproduces  the  same  words  in  correspond- 
ence with  the  traces  registered.  "  The  first  function  of  this 
instrument  is  not  the  result  of  a  new  discovery.  Physicists 
have  long  sought  to  solve  the  problem  of  registering  speech, 
and  in  1856  Mr.  Leo  Scott  invented  an  instrument  well  known 
to  physicists  under  the  name  of  phonautograph,  which  com- 
pletely solved  the  difficulty  :  this  instrument  is  described  in  all 
the  more  detailed  treatises  on  physics.  But  the  second  function 
of  the  Edison  instrument  was  not  realized  nor  even  mentioned 
by  Mr.  Scott,  and  we  are  surprised  that  this  able  inventor  should 
have  regarded  Mr.  Edison's  invention  as  an  injurious  act  of 
spoliation.  We  regret  on  his  own  account,  since  no  one  has 
wished  to  deprive  him  of  the  credit  he  deserves,  that  he  should 
have  published  a  pamphlet  on  the  subject,  couched  in  terms  of 
such  asperity,  which  proves  nothing,  and  only  states  facts  which 
were  well  known  to  all  physicists.  If  any  other  person  could 
claim  the  invention  of  the  phonograph,  at  least  in  its  most  cu- 
rious property  of  reproducing  speech,  it  would  certainly  be  M. 
Charles  Cros ;  for  in  a  sealed  paper  deposited  at  the  Academic 
des  Sciences,  April  30th,  1877,  he  pointed  out  the  principle  of 
an  instrument  by  means  of  which  speech  might  be  reproduced 
in  accordance  with  the  marks  traced  on  a  register  like  that  of 


236  THE    PHONOGRAPH. 

the  phonautograph.1     Mr.  Edison's  patent,  in  which  the  princi- 

1  I  give  the  text  of  M.  Cros's  sealed  paper,  opened  by  his  request,  at 
the  Academic  des  Sciences,  December  3d,  1877:  "Speaking  generally,  my 
process  consists  in  obtaining  traces  of  the  movement  to  and  fro  of  a 
vibrating  membrane,  and  in  using  this  tracing  to  reproduce  the  same  move- 
ments, with  their  intrinsic  relations  of  duration  and  intensity,  either  on  the 
same  membrane,  or  on  one  adapted  to  give  out  the  sounds  which  result 
from  this  series  of  movements. 

"  It  is  therefore  necessary  that  an  extremely  delicate  tracing,  such  as  may 
be  obtained  by  passing  a  needle  over  a  surface  blackened  by  fire,  should 
be  transformed  into  a  tracing,  capable  of  sufficient  resistance  to  guide  an 
index  which  will  transmit  its  movements  to  the  membrance  of  sound. 

"A  light  index  is  fastened  to  the  centre  of  a  vibrating  membrane;  it 
terminates  in  a  point  (a  metallic  wire  or  tip  of  a  feather)  which  rests  on  a 
surface  which  has  been  blackened  by  fire.  This  surface  forms  part  of  a 
disk,  to  which  the  double  action  of  rotation  and  rectilinear  progression  has 
been  given.  If  the  membrane  is  at  rest,  the  point  will  trace  a  simple  spi- 
ral ;  if  the  membrane  vibrates,  tbere  will  be  undulations  in  the  spiral,  and 
these  undulations  will  represent  the  precise  movements  of  the  membrane 
in  their  duration  and  intensity. 

"  By  a  well-known  photographic  process,  a  transparent  tracing  of  the 
undulations  of  the  spiral  can  be  represented  by  a  line  of  similar  dimen- 
sions on  some  resisting  substance — tempered  steel,  for  example. 

"  When  this  is  done,  this  resisting  surface  is  placed  in  a  turning  machine, 
which  causes  it  to  revolve  and  advance  with  a  velocity  and  motion  similar 
to  those  by  which  the  registering  surface  was  actuated.  A  metallic  point, 
if  the  tracing  is  concave,  or  a  grooved  index  if  it  is  in  relief,  is  kept  upon 
the  tracing  by  a  spring,  and  the  index  which  supports  this  point  is  con- 
nected with  the  centre  of  the  membrane  which  produces  the  sounds.  Un- 
der these  conditions,  the  membrane  will  be  actuated  not  by  the  vibrating 
air,  but  by  the  tracing  which  guides  the  index,  and  the  impulses  will  be 
precisely  similar  in  duration  and  intensity  to  those  to  which  the  registering 
membrane  was  subjected. 

"  The  spiral  tracing  represents  equal  successions  of  time  by  increasing 
or  decreasing  lengths.  There  is  no  inconvenience  in  this,  since  the  turns 
of  the  spiral  are  very  close  together,  if  only  the  circumference  of  the  turn- 
ing circle  is  used ;  but  then  the  central  surface  is  lost. 

"  In  all  cases  the  tracing  of  the  helix  on  a  cylinder  is  much  more  satis- 
factory, and  I  am  now  trying  to  make  this  idea  practicable." 


EDISON'S  PATENT.  237 

pie  of  the  phonograph  is  first  indicated,  is  dated  July  31st,  1877, 
and  he  was  still  only  occupied  with  the  repetition  of  the  Morse 
signals.  In  this  patent  Mr.  Edison  described  a  mode  of  regis- 
tering these  signals  by  means  of  indentations  traced  with  a 
stylus  on  a  sheet  of  paper  wound  round  a  cylinder,  and  this 
cylinder  had  a  spiral  groove  cut  on  its  surface.  The  tracings 
thus  produced  were  to  be  used  for  the  automatic  transmission 
of  the  same  message,  by  passing  it  again  under  a  stylus  which 
should  react  on  a  current  breaker.  In  this  patent,  therefore, 
nothing  is  said  of  the  registration  of  speech  or  of  its  reproduc- 
tion; but,  as  the  Telegraphic  Journal  of  May  1st,  1878,  ob- 
serves, the  foregoing  invention  gave  him  the  means  of  solving 
this  double  problem  as  soon  as  it  was  suggested  to  him.  If 
we  may  believe  the  American  journals,  this  suggestion  soon 
came,  and  it  was  the  result  of  an  accident. 

In  the  course  of  some  experiments  Mr.  Edison  was  making 
with  the  telephone,  a  stylus  attached  to  the  diaphragm  pierced 
his  finger  at  the  moment  when  the  diaphragm  began  to  vibrate 
under  the  influence  of  the  voice,  and  the  prick  was  enough  to 
draw  blood.  It  then  occurred  to  him  that  if  the  vibrations  of 
the  diaphragm  enabled  the  stylus  to  pierce  the  skin,  they  might 
produce  on  a  flexible  surface  such  distinct  outlines  as  to  repre- 
sent all  the  undulations  produced  by  the  voice,  and  even  that 
the  same  outlines  might  mechanically  reproduce  the  vibrations 
which  had  caused  them,  by  reacting  on  a  plate  capable  of  vi- 
brating in  the  same  way  as  that  which  he  had  already  used  for 
the  reproduction  of  the  Morse  signals.  From  that  moment  the 
phonograph  was  discovered,  since  there  was  only  a  step  between 
the  idea  and  its  realization,  and  in  less  than  two  days  the  in- 
strument was  made  and  tried. 

This  is  an  ingenious  story,  yet  we  would  rather  believe  that 
the  discovery  was  made  in  a  more  serious  spirit.  In  fact, -such 
an  inventor  as  Mr.  Edison,  who  had  discovered  the  electro- 
motograph  and  had  applied  it  to  the  telephone,  was  already  on 


238  THE   PHONOGRAPH. 

the  way  to  discover  the  phonograph,  and  we  think  too  well  of 
his  powers  to  attach  much  credit  to  this  American  romance. 
Besides,  Mr.  Edison  was  well  acquainted  with  Mr.  Scott's  phon- 
autograph. 

Mr.  Edison's  phonograph  was  only  patented  in  January, 
1877.  Consequently,  when  we  look  at  the  principle  of  the  in- 
vention, M.  Cros  undoubtedly  may  claim  priority ;  but  it  is  a 
question  whether  the  system  described  in  his  sealed  paper,  and 
published  in  the  Semaine  du  Clerge,  October  8th,  1877,  would 
have  been  capable  of  reproducing  speech.  Our  doubt  seems 
justified  by  the  unsuccessful  attempts  of  the  Abbe  Leblanc  to 
carry  out  M.  Cros's  idea.  When  we  have  to  do  with  such  un- 
dulating and  complex  vibrations  as  those  involved  in  the  re- 
production of  articulate  words,  it  is  necessary  that  the  stereo- 
typing should  in  some  sense  be  effected  by  the  words  them- 
selves, and  their  artificial  reproduction  will  necessarily  fail  to 
mark  the  slight  differences  which  distinguish  the  delicate  com- 
binations of  speech.  Besides,  the  movements  performed  by  a 
point  confined  to  a  groove  that  follows  a  sinusoidal  curve  can- 
not be  effected  with  all  the  freedom  necessary  for  the  develop- 
ment of  sounds,  and  the  friction  exerted  on  the  two  edges  of 
the  groove  will  often  be  of  a  nature  to  stifle  them.  A  distin- 
guished member  of  the  Societe  de  Physique,  when  I  exhibited 
the  phonograph  to  that  society,  justly  said  that  Mr.  Edison's 
whole  invention  consisted  in  the  thin  metallic  sheet  on  which 
the  vibrations  are  inscribed  ;  this  sheet  permits  the  movements 
of  the  vibrating  plate  to  be  directly  stereotyped,  and  thereby 
the  problem  is  solved.  It  was  necessary  to  find  such  an  expe- 
dient, and  it  was  done  by  Mr.  Edison,  who  is  therefore  the  in- 
ventor of  the  phonograph. 

After  M.  Cros,  and  before  Mr.  Edison,  MM.  Napoli  and  Mar- 
cel Deprez  attempted  to  make  a  phonograph,  but  with  so  little 
success  that  they  believed  at  one  time  the  problem  to  be  in- 
soluble, and  threw  doubts  on  Mr.  Edison's  invention  when  it 


EDISON'S  PATENT.  239 

was  announced  to  the  Societe  de  Physique.  They  subsequent- 
ly resumed  their  labors,  and  lead  us  to  hope  that  they  may 
eventually  produce  a  phonograph  of  more  perfect  construction 
than  that  of  Mr.  Edison.  We  shall  have  more  to  say  on  this 
subject. 

In  conclusion,  the  mechanical  reproduction  of  speech  was 
first  effected  by  Mr.  Edison,  and  in  so  doing  he  has  accom- 
plished one  of  the  most  curious  and  important  discoveries  of 
our  time,  since  it  has  shown  that  this  reproduction  was  much 
less  complicated  than  had  been  supposed.  Yet  the  theoretical 
consequences  of  the  discovery  must  not  be  exaggerated,  since  I 
do  not  consider  it  by  any  means  proved  that  our  theories  on 
the  voice  are  incorrect.  There  is,  in  fact,  a  great  difference  be- 
tween the  reproduction  of  a  sound'which  has  been  uttered,  and 
the  mode  in  which  the  same  sound  was  produced.  The  repro- 
duction may  be  easily  effected,  as  M.  Bourseul  has  remarked,  as 
soon  as  a  mode  has  been  discovered  of  transmitting  the  vibra- 
tions of  air,  however  complex  they  may  be ;  but  in  order  to 
produce  the  complex  vibrations  of  speech  by  the  voice,  several 
special  organs  must  be  exercised — first,  the  muscles  of  the 
throat ;  secondly,  the  tongue,  the  lips,  and  even  the  teeth — 
and  for  this  reason  an  articulating  machine  is  necessarily  very 
complex. 

Surprise  was  expressed  that  the  speaking  machine,  which 
was  brought  from  America  two  years  ago,  and  exhibited  at  the 
Grand  Hotel,  Paris,  was  so  extremely  complicated,  since  the 
phonograph  solved  the  problem  in  such  a  simple  way.  This 
is  because  the  latter  instrument  only  reproduces  speech,  while 
the  former  utters  it,  and  the  inventor  of  the  speaking  machine 
had  to  employ  in  his  mechanism  all  the  organs  which  are  nec- 
essary in  our  organism  for  the  reproduction  of  speech.  The 
problem  was  infinitely  more  complex,  and  this  invention  has 
not  attracted  all  the  attention  it  deserved.  We  shall  speak  of 
it  presently.  We  must  now  describe  the  phonograph,  and  the 


240 


THE    PHONOGRAPH. 


different  applications  which  have  been,  or  which  may  be,  made 
of  it. 

Description  of  the  Phonograph,  and  Mode  of  Using  it. — The 
first  and  best-known  model  of  this  instrument,  which  we  rep- 
resent in  Fig.  66,  simply  consists  of  a  registering  cylinder,  11, 
set  in  motion  with  the  hand  by  a  winch,  M,  before  which  a 
vibrating  plate  is  placed,  furnished  on  its  face  with  a  telephone 
mouth-piece,  E,  and  on  the  reverse  side  with  a  tracing-point. 
This  tracing-point,  which  is  seen  at  6-  in  the  section  of  the  in- 
strument given  in  Fig.  68,  is  not  fixed  directly  on  the  plate ;  it 

C 


FIG.  66. 

rests  on  a  spring,  r,  and  a  caoutchouc  pad,  c,  is  placed  between 
it  and  the  vibrating  disk.  This  pad  is  formed  of  the  end  of  a 
tube  which  is  designed  to  send  the  vibrations  of  the  plate  to 
the  point  s  without  stifling  them.  Another  pad,  a,  placed  be- 
tween the  plate  L  L  and  the  rigid  support  of  the  point,  mod- 
erates in  some  degree  these  vibrations,  which,  without  this 
precaution,  would  generally  be  too  powerful. 

The  cylinder,  of  which  the  axis  A  A  (Fig.  66)  is  cut  at  one 
end  like  a  screw,  to  enable  it  to  make  a  lateral  progressive 


DESCRIPTION    OF   THE    INSTRUMENT.  241 

movement  simultaneously  with  the  rotatory  movement  effected 
on  itself,  has  on  its  surface  a  narrow  screw-thread  coinciding 
with  that  of  the  axis;  and  when  the  tracing-point  is  inserted, 
it  is  able  to  pass  along  it  for  a  distance  corresponding  to  the 
time  occupied  in  turning  the  cylinder.  A  sheet  of  tin-foil  or 
of  very- thin  copper  is  carefully  applied  to  the  surface  of  the 
cylinder,  and  it  should  be  slightly  pressed  down  upon  it,  so  as 
to  show  a  faint  tracing  of  the  groove,  and  to  allow  the  point 
of  the  vibrating  disk  to  be  placed  in  a  proper  position.  The 
point  rests  on  the  foil  under  a  pressure  which  must  be  regu- 
lated, and  for  this  purpose,  as  well  as  to  detach  the  cylinder 
when  it  is  desired  to  place  or  take  away  the  tin-foil,  there  is 
the  articulated  system  S  N,  which  sustains  the  support  S  of 
the  vibrating  disk.  This  system  consists  of  a  jointed  lever  in 
which  there  is  a  nut-screw  for  the  screw  R.  The  handle  N  at 
the  end  of  the  lever  allows  the  tracing  system  to  be  turned 
aside  when  the  screw  R  is  loosened.  In  order  to  regulate  the 
pressure  of  the  tracing-point  on  the  sheet  of  tin-foil,  it  is  enough 
to  turn  the  screw  R  loosely  in  its  socket,  and  to  tighten  it  as 
soon  as  the  right  degree  of  pressure  is  obtained. 

This  is  the  simple  system  by  which  speech  can  engrave  itself 
'on  a  plate  in  durable  characters,  and  it  works  in  the  following 
manner : 

The  speaker  stands  before  the  mouth-piece  E,  as  before  a 
telephone  or  an  acoustic  tube,  and  speaks  in  a  strong,  emphatic 
voice,  with  his  lips  pressed  against  the  walls  of  the  mouth- 
piece, as  we  see  in  Fig.  67 ;  at  the  same  moment  he  turns  the 
handle  of  the  cylinder,  which  is  provided  with  a  heavy  fly- 
wheel in  order  that  the  movement  may  be  regular.  Influenced 
by  the  voice,  the  plate  L  L  begins  to  vibrate,  and  sets  the  trac- 
ing-point at  work,  which  presses  on  the  tin-foil  at  each  vibra- 
tion, and  produces  a  furrow  whose  depth  varies  along  its  course 
in  correspondence  with  the  unequal  vibrations  of  the  disk. 
The  cylinder  which  moves  at  the  same  time  presents  the  differ- 

11 


242  THE  PHONOGRAPH. 

ent  parts  of  the  groove  of  which  we  have  spoken  to  the  trac- 
ing-point in  succession;  so  that,  when  the  spoken  sentence 
comes  to  an  end,  the  design  which  has  been  pricked  out,  con- 


FIG.  6T. 


sisting  of  a  succession  of  reliefs  and  depressions,  represents  the 
registration  of  the  sentence  itself.  The  first  part  of  the  op- 
eration is  therefore  accomplished,  and  by  detaching  the  sheet 
from  the  instrument  the  words  may  be  put  away  in  a  portfolio. 
We  have  now  to  see  how  the  instrument  is  able  to  reproduce 
what  has  been  so  easily  inscribed. 

For  this  purpose  it  is  only  necessary  to  repeat  the  process, 
and  the  identical  effect  will  be  reproduced  in  an  inverse  sense. 
The  tracing  stylus  is  replaced  at  the  end  of  the  groove  it  has 
already  traversed,  and  the  cylinder  is  again  set  in  motion. 
When  the  engraved  track  passes  again  under  the  point,  it  has 
a  tendency  to  raise  it,  and  to  impart  to  it  movements  which 
must  necessarily  be  the  repetition  of  those  which  first  produced 
the  tracing.  The  vibrating  plate  is  obedient  to  these  move- 
ments, and  begins  to  vibrate,  thus  reproducing  the  same 
sounds,  and  consequently  the  same  words ;  yet  since  there  is 
necessarily  a  loss  of  power  in  this  double  transformation  of 


REPRODUCTION   OF   WORDS. 


243 


mechanical  effects,  the  speaking-tube  C  is  attached  to  the 
mouth-piece  E  in  order  to  intensify  the  effects.  Under  these 
conditions  the  words  reproduced  by  the  instrument  may  be 
heard  in  all  parts  of  a  hall,  and  it  is  startling  to  hear  this  voice 
— somewhat  shrill,  it  must  be  admitted — which  seems  to  utter 
its  sentences  from  beyond  the  grave.  If  this  invention  had 
taken  place  in  the  Middle  Ages,  it  would  certainly  have  been 
applied  to  ghostly  apparitions,  and  it  would  have  been  invalu- 
able to  miracle-mongers. 


As  the  height  of  the  notes  of  the  musical  scale  depends  on 
the  number  of  vibrations  effected  by  a  vibrating  substance  in 
a  given  time,  speaking  will  be  reproduced  in  a  tone  of  which 
the  pitch  will  depend  on  the  velocity  of  rotation  given  to  the 
cylinder  on  which  the  tin-foil  is  wound.  If  the  velocity  is  the 
same  as  that  which  was  used  in  registration,  the  tone  of  the 


244  THE    PHONOGRAPH. 

words  reproduced  is  the  same  as  that  in  which  they  were 
uttered.  If  the  velocity  is  greater,  the  tone  is  higher ;  if  less, 
the  tone  is  lower ;  but  the  accent  of  the  speaker  may  always  be 
recognized.  Owing  to  this  peculiarity  the  reproduction  of  songs 
is  nearly  always  defective  in  instruments  turned  by  the  hand ; 
they  sing  out  of  tune.  This  is  not  the  case  when  the  instrument 
is  moved  by  a  well-regulated  system  of  clock-work,  and  in  this 
way  a  satisfactory  reproduction  of  a  duet  has  been  obtained. 

The  words  registered  on  tin-foil  can  be  often  reproduced; 
but  the  sounds  become  fainter  and  more  indistinct  at  each  rep- 
etition, since  the  tracings  in  relief  are  gradually  effaced.  The 
reproduction  on  copper  is  more  successful,  but  if  intended  to 
be  permanent  the  sheets  must  be  stereotyped,  and  in  this  case 
the  instrument  must  be  differently  arranged. 

An  attempt  has  been  made  to  obtain  speech  from  the 
phonograph  by  taking  the  words  registered  inversely  to  their 
true  direction.  In  this  way  the  sounds  obtained  were  necessa- 
rily quite  unlike  the  words  uttered ;  yet  Messrs.  Fleeming  Jen- 
kin  and  Ewing  have  observed  that  not  only  are  the  vowels  un- 
changed by  this  inverse  action,  but  consonants,  syllables,  and 
even  whole  words  may  be  reproduced  with  the  accent  they 
would  have  if  spoken  backward. 

The  sounds  produced  by  the  phonograph,  although  fainter 
than  those  of  the  voice  which  produced  the  registered  tracing, 
are  strong  enough  to  react  on  the  ordinary  string  telephone, 
and  even  on  a  Bell  telephone;  and  as  in  this  case  the  sounds 
do  not  go  beyond  the  instrument,  and  can  only  be  heard  by 
the  person  who  is  using  it,  it  is  easy  to  ascertain  that  the 
sound  has  not  been  produced  by  trickery. 

Mr.  Edison  presented  his  phonograph  to  the  Academic  des 
Sciences  through  me,  March  llth,  1878,  and  when  his  agent, 
M.  Puskas,  caused  the  wonderful  instrument  to  speak,  a  mur- 
mur of  admiration  was  heard  from  all  parts  of  the  hall  —  a 
murmur  succeeded  by  repeated  applause.  A  letter  appeared 


RECEPTION   BY   THE    ACADEMY.  245 

in  the  newspapers  from  one  of  the  persons  present,  in  which 
he  said  that  "  the  learned  Academy,  generally  so  cold,  had  nev- 
er before  abandoned  itself  to  such  enthusiasm.  Yet  some  mem- 
bers of  a  sceptical  turn  of  mind,  instead  of  examining  the 
physical  fact,  ascribed  it  to  moral  causes,  and  a  report  soon 
ran  through  the  room  which  seemed  to  accuse  the  Academy  of 
having  been  mystified  by  a  clever  ventriloquist.  Certainly  the 
spirit  of  ancient  Gaul  is  still  to  be  found  among  the  French, 
and  even  in  the  Academy.  One  said  that  the  sounds  emitted 
by  the  instrument  were  precisely  those  of  a  ventriloquist. 
Another  asked  if  the  movements,  of  M.  Puskas's  face  and  lips 
as  he  turned  the  instrument  did  not  resemble  the  grimaces  of 
a  ventriloquist.  A  third  admitted  that  the  phonograph  might 
emit  sounds,  but  believed  that  it"  was  much  helped  by  the 
manipulator.  Finally,  the  Academy  requested  M.  du  Moncel 
to  try  the  experiment,  and  as  he  was  not  accustomed  to  speak 
into  the  instrument,  it  was  unsuccessful,  to  the  great  joy  of  the 
incredulous.  Some  members  of  the  Academy,  however,  desir- 
ing to  ascertain  the  real  nature  of  the  effects,  begged  M.  Pus- 
kas  to  repeat  the  experiments  before  them  in  the  secretary's 
office,  under  such  conditions  as  they  should  lay  down.  M. 
Puskas  complied  with  this  request,  and  they  were  absolutely 
satisfied  with  the  result.  Yet  others  remained  incredulous, 
and  it  was  necessary  that  they  should  make  the  experiment 
for  themselves  before  they  accepted  the  fact  that  speech  could 
be  reproduced  in  so  simple  a  way." 

The  anecdote  I  have  just  related  cannot  be  interpreted  to 
the  discredit  of  the  Academic  des  Sciences,  since  it  is  especial- 
ly bound  to  preserve  the  true  principles  of  science  intact,  and 
only  to  accept  startling  facts  after  a  careful  examination.  Ow- 
ing to  this  attitude,  all  which  emanates  from  the  Academy 
can  be  received  with  complete  confidence;  and  we  cannot  ap- 
prove too  highly  of  reserve  which  does  not  give  way  to  the 
first  impulse  of  enthusiasm  and  admiration. 


246  THE    PHONOGRAPH. 

The  failure  of  my  experiment  at  the  Academy  was  simply 
due  to  the  fact  that  I  spoke  at  too  great  a  distance  from  the 
vibrating  disk,  and  that  my  lips  did  not  touch  the  sides  of  the 
mouth-piece.  Some  days  later,  at  the  request  of  several  of  my 
colleagues,  I  made  repeated  trials  of  the  instrument,  and  I 
soon  succeeded  in  making  it  speak  as  well  as  the  supposed 
ventriloquist;  but  I  learned  at  the  same  time  that  practice  is 
necessary  to  insure  success.  Some  words  are  reproduced  more 
readily  than  others;  those  which  include  many  vowels  and 
many  r's  come  out  better  than  those  which  abound  in  conso- 
nants, and  especially  in  s's.  It  is,  therefore,  not  surprising 
that,  even  in  the  case  of  an  experienced  manipulator  like  Mr. 
Edison's  agent,  some  of  the  sentences  uttered  by  him  are  more 
audible  than  others. 

The  simultaneous  repetition  of  several  sentences  in  different 
languages  by  registering  one  over  the  other  is  one  of  the  most 
surprising  effects  of  the  phonograph.  As  many  as  three  dif- 
ferent sentences  have  been  obtained ;  but  in  order  to  distin 
guish  them  through  the  confused  sounds  which  result  from 
placing  one  over  the  other, -it  is  necessary  that  different  per- 
sons, giving  special  attention  to  a  particular  sentence,  should 
thus  separate  them  and  understand  their  sense.  Vocal  airs 
may,  in  the  same  way,  be  registered  over  the  word  tracings, 
and  in  this  case  it  is  more  easy  to  distinguish  them. 

There  are  several  models  of  phonographs.  The  one  repre- 
sented in  Fig.  66  has  been  chiefly  used  for  public  experiments ; 
but  there  is  a  small  model,  generally  sold  to  the  public,  in 
which  the  cylinder  is  much  longer,  and  serves  at  once  for  reg- 
ister and  fly-wheel.  This  instrument  gives  good  results,  but 
can  only  be  used  for  short  sentences.  In  this  model,  as  in- 
deed in  the  other,  the  words  are  more  easily  registered  by  fas- 
tening a  small  tube  in  the  form  of  a  prolonged  speaking- 
trumpet  to  the  mouth-piece ;  the  vibrations  of  the  air  are  thus 
concentrated  on  the  vibrating  disk,  and  act  with  greater  ener- 


CLOCK-WORK   SYSTEM.  247 

gy.  The  tenuity  of  the  vibrating  disk  adds  to  the  efficiency 
of  the  instrument,  and  the  tracing-point  may  be  fitted  directly 
to  this  disk. 

I  need  not  describe  particularly  the  phonograph  which  acts 
by  clock-work.  The  instrument  resembles  the  one  represented 
in  Fig.  66,  except  that  it  is  mounted  on  a  rather  high  table, 
to  give  room  for  the  descent  of  the  weight  which  moves  the 
clock-work;  the  mechanism  is  applied  directly  to  the  axis  of 
the  cylinder,  supplying  the  place  of  the  winch,  and  is  regulated 
by  a  small  fly-wheel.  The  wheel  used  in  an  English  system 
has  been  adopted,  but  we  prefer  that  of  M.  Villarceau,  which 
has  small  wings. 

Since  it  is  always  difficult  to  fit  the  tin-foil  to  the  cylinder, 
Mr.  Edison  has  tried,  with  good  success,  to  obtain  the  tracing 
on  a  plane  surface  of  tin  -  foil,  by  means  of  the  arrangement 
represented  in  Fig.  69.  In  this  new  model,  the  plate  on  which 


FIG. 


the  tin  or  copper  sheet  is  to  be  applied  has  a  spiral  grooving, 
of  which  one  end  corresponds  to  the  centre  of  the  plate,  and 
the  other  to  its  outer  edges.  The  plate  is  set  in  motion  by  a 
powerful  system  of  clock-work,  of  which  the  velocity  is  regu- 
lated with  reference  to  the  length  of  the  turns  of  the  spiral. 
The  vibrating  disk  is  arranged  as  in  the  former  instrument,  and 


248 


THE   PHONOGRAPH. 


is  placed  above  this  plate  ;  the  tracing-point  may,  by  means  of 
a  movement  of  progression  imparted  to  the  system,  follow  the 
spiral  groove  from  the  centre  of  the  plate  to  its  circumference. 
It  must  not  be  supposed  that  all  the  tin-foil  used  for  phono- 
graphic registration  is  equally  good.  The  foil  must  be  of  a 
definite  thickness,  and  combined  with  a  definite  amount  of  lead. 
That  which  is  used  for  wrapping  chocolate,  and  indeed  all  foil 
of  French  manufacture,  is  too  thin  and  too  exclusively  made  of 


FIG.  70. 

tin  to  produce  good  results,  and  M.  Puskas  was  obliged  to  im- 
port some  from  America  to  continue  his  experiments.  The 
relative  proportion  of  lead  and  tin  has  not  yet  been  defined, 
and  the  selection  of  foil  has  been  made  empirically ;  but  as  the 
use  of  the  phonograph  becomes  more  general,  this  proportion 
must  be  ascertained,  and  it  may  easily  be  done  by  analyzing 
the  composition  of  the  foil  which  gives  the  best  results. 


THE   TEACING-POINT.  249 

The  arrangement  of  the  tracing  -  point  is  also  of  much  im- 
portance for  the  successful  action  of  the  phonograph.  It  must 
be  very  slender  and  very  short  (not  exceeding  a  millimetre  in 
length),  so  as  to  register  distinctly  the  smallest  vibrations  of 
the  vibrating  disk  without  deviating  from  the  normal  direction 
of  the  cylinder,  which  might  be  the  case  if  it  were  long,  on  ac- 
count of  the  unequal  friction  exerted  on  the  tin-foil.  It  must 
also  be  made  of  a  metal  which  has  no  tendency  to  tear  the  me- 
tallic sheet.  Iron  appears  to  combine  most  of  the  conditions 
demanded. 

The  phonograph  is  still  in  its  infancy,  and  it  is  probable  that 
it  may  soon  be  enabled  to  register  speech  without  the  necessity 
of  speaking  into  a  mouth-piece.  According  to  the  newspapers, 
Mr.  Edison  has  already  discovered  a  way  of  collecting,  without 
the  aid  of  an  acoustic  tube,  the  sounds  uttered  at  a  distance  of 
three  or  four  feet  from  the  instrument,  and  of  printing  them 
on  a  metallic  sheet.  From  this  there  is  only  a  step  to  the 
power  of  inscribing  a  speech  uttered  in  a  large  hall  at  any  dis- 
tance from  the  phonograph ;  and  if  this  step  is  taken,  phonog- 
raphy may  be  substituted  with  advantage  for  short-hand.  We 
add  in  a  note  the  instructions  given  by  M.  Roosevelt  to  the 
purchasers  of  phonographs,  so  as  to  enable  them  to  work  the 
instrument.1 

1  Never  make  a  contact  between  the  stylus  and  the  cylinder  until  the 
latter  is  covered  with  the  tin-foil.  Do  not  begin  to  turn  the  cylinder  until 
assured  that  everything  is  in  its  place.  Take  care,  when  the  stylus  returns 
to  the  point  of  departure,  to  bring  the  mouth-piece  forward.  Always  leave 
a  margin  of  from  five  to  ten  millimetres  on  the  left  and  at  the  beginning 
of  the  sheet  of  tin-foil ;  for  if  the  stylus  describes  the  curve  on  the  ex- 
treme edge  of  the  cylinder,  it  may  tear  the  sheet  or  come  out  of  the  groove. 
Be  careful  not  to  detach  the  spring  of  the  caoutchouc  pad. 

To  fix  the  tin-foil,  apply  varnish  to  the  end  with  a  paint-brush ;  take 
this  end  between  the  finger  and  thumb  of  the  left  hand,  with  the  sticky 
part  toward  the  cylinder ;  raise  it  with  the  right  hand  and  apply  it  quite 
smoothly  to  the  cylinder ;  bring  round  the  sticky  end,  and  join  them  firmly. 

11* 


250  THE  PHONOGRAPH. 

Considerations  on  the  Theory.  —  Although  the  explanation 
we  have  given  will  make  the  effects  of  the  phonograph  intelli- 

To  adjust  the  stylus,  and  place  it  in  the  centre  of  the  groove,  bring  the 
cylinder  to  the  right,  so  as  to  place  the  stylus  opposite  the  left  extremity 
of  the  tin-foil ;  bring  forward  the  cylinder  gently  and  by  degrees,  until  the 
stylus  touches  the  tin-foil  with  force  enough  to  imprint  a  mark.  Observe 
if  this  mark  is  quite  in  the  centre  of  the  groove  (in  order  to  do  this,  make 
a  mark  with  the  nail  across  the  cylinder),  and  if  it  is  not,  adjust  the  stylus 
to  the  right  or  left  by  means  of  the  little  screw  placed  above  the  mouth- 
piece. The  depth  of  the  impression  made  by  the  stylus  should  be  one- 
third  millimetre,  just  enough  for  it  to  leave  a  slight  tracing,  whatever  the 
range  of  vibrations  may  be. 

To  reproduce  the  words,  the  winch  must  be  turned  with  the  same  veloc- 
ity as  when  they  were  inscribed.  The  average  velocity  should  be  about 
eighty  turns  a  minute. 

In  speaking,  the  lips  must  touch  the  mouth-piece,  and  deep  guttural 
sounds  are  better  heard  than  those  which  are  shrill.  In  reproducing,  the 
tightening  screw  must  be  loosened  and  brought  in  front  of  the  mouth- 
piece, the  cylinder  must  be  brought  back  to  its  point  of  departure,  the  con- 
tact between  the  stylus  and  the  foil  must  be  renewed,  and  the  cylinder  must 
again  be  turned  in  the  same  direction  as  when  the  sentence  was  spoken. 

To  increase  the  volume  of  reproduced  sound,  a  tube  of  card-board,  wood, 
or  horn  may  be  applied  to  the  mouth-piece  ;  it  must  be  of  a  conical  form, 
and  its  lower  end  should  be  rather  larger  than  the  opening  of  the  mouth- 
piece. 

The  stylus  consists  of  a  No.  9  needle,  somewhat  flattened  on  its  two 
sides  by  friction  on  an  oiled  stone.  The  caoutchouc  pad  which  connects 
the  plate  with  the  disk  serves  to  weaken  the  vibrations  of  the  plate.  If 
this  pad  should  come  off,  heat  the  head  of  a  small  nail,  apply  it  to  the 
wax  which  fastens  the  pad  to  the  plate  or  to  the  spring,  so  as  to  soften 
it ;  then  press  the  caoutchouc  lightly,  until  it  adheres  to  the  place  from 
which  it  was  detached.  The  pads  must  be  renewed  from  time  to  time,  as 
they  lose  their  elasticity.  Care  must  be  taken,  in  replacing  them,  not  to 
injure  the  vibrating  plate,  either  by  too  strong  a  pressure  or  by  grazing  it 
with  the  instrument  employed  to  fix  the  pad. 

The  first  experiments  should  be  with  single  words  or  very  short  sen- 
tences, which  can  be  extended  as  the  ear  becomes  accustomed  to  the  in- 
strument's peculiar  tone. 


THEORY  OP  THE  PHONOGRAPH.  251 

gible,  it  leads  to  a  curious  question  which  has  greatly  interest- 
ed physicists — namely,  how  it  is  that  the  tracing  made  on  so 
yielding  a  surface  as  tin  can,  when  retraced  by  the  stylus,  of 
which  the  rigidity  is  relatively  great,  produce  a  vibratory  move- 
ment without  being  completely  destroyed.  To  this  we  reply 
that  the  retracing  is  effected  with  such  extreme  rapidity  that 
the  effects  of  active  force  which  are  developed  only  manifest 
themselves  locally,  and  that  under  these  conditions  the  me- 
chanical effects  exerted  are  as  energetic  in  soft  as  in  hard 
substances.  The  curious  experiment,  related  in  so  many  books 
on  physics,  must  be  remembered,  of  a  plank  pierced  when  a 
candle  serves  as  the  projectile  of  a  gun.  The  various  acci- 
dents caused  by  the  discharge  of  paper  waddings  must  also  be 
remembered.  Under  such  conditions  the  motion  imparted  to 
the  molecules  which  receive  the  shock  has  not  time  to  be  trans- 
mitted to  the  whole  mass  of  the  substance  to  which  they  be- 
long, and  these  molecules  are  compelled  to  separate  from  it,  or 
at  any  rate  to  produce,  when  the  substance  is  capable  of  vibra- 
tion, a  centre  of  vibration  which  diffuses  waves  throughout  its 
surface,  and  produces  sounds. 

Several  scientific  men  —  among  others  Messrs.  Preece  and 
Mayer — have  carefully  studied  the  form  of  the  tracing  left  by 
the  voice  on  the  tin-foil  of  the  phonograph,  and  they  observe 
that  it  greatly  resembles  the  outline  of  the  singing  flames  so 
well  shown  by  Herr  Koenig's  instruments.  Mr.  Mayer  wrote 
on  this  subject  in  the  Popular  Science  Monthly  Review  of 
April,  1878. 

He  said  that  he  had  been  successful  in  reproducing  a  splen- 

The  tone  is  varied  by  accelerating  or  slackening  the  rotatory  movement 
of  the  cylinder.  The  cries  of  animals  may  be  imitated.  Instrumental 
music  may  be  reproduced  by  placing  a  card-board  tube  before  the  mouth- 
piece. The  airs  should  be  played  in  rapid  time,  since,  when  there  is  no 
system  of  clock-work,  they  will  be  more  perfectly  reproduced  than  those 
which  are  played  slowly. 


252  THE    PHONOGKAPH. 

did  tracing  on  smoked  glass,  which  gave  in  profile  the  outline 
of  the  vibrations  of  sound  registered  on  the  tin-foil  with  their 
varying  curves.  For  this  purpose  he  fastened  to  the  spring 
support  of  the  tracing-point  of  the  phonograph  a  slender  rod, 
terminating  in  a  point,  which  pressed  obliquely  against  the 
plate  of  smoked  glass,  and,  since  the  latter  was  in  a  vertical  po- 
sition, a  movement  imparted  to  the  rod  enabled  it  to  produce 
a  sinusoidal  tracing.  By  this  arrangement,  when  the  phono- 
graph was  at  work,  two  systems  of  tracings  were  produced  at 
the  same  moment,  of  which  one  was  the  profile  of  the  other. 

Mr.  Mayer  had  not,  at  the  time  he  wrote,  been  long  enough 
in  possession  of  the  instrument  to  make  many  experiments 
with  it,  but  from  a  study  of  some  of  its  curves  it  appeared  to 
him  that  the  registered  outlines  bore  a  strong  resemblance  to 
those  of  Koenig's  singing  flames. 

•    ©O       O    O     QO       G2     o    OO       €13  A 


FIG.  Tl. 

Fig.  71  represents  the  tracing  which  corresponds  to  the  let- 
ter a  when  pronounced  as  in  bat,  in  the  three  systems  of  regis- 
tration. That  corresponding  to  line  A  is  an  enlarged  repro- 
duction of  the  tracing  left  on  the  tin-foil ;  that  corresponding 
to  line  B  represents  its  profile  on  the  sheet  of  smoked  glass. 
Finally,  line  C  shows  the  outline  of  Koenig's  singing  flames, 
when  the  same  sound  is  produced  quite  close  to  the  membrane 
of  the  register.  It  must  be  quite  close,  since  the  form  of  the 
tracing  produced  by  a  pointer  attached  to  a  vibrating  mem- 
brane, when  influenced  by  composite  sounds,  depends  on  the 


253 

distance  intervening  between  the  membrane  and  the  source  of 
sound,  and  an  infinite  variety  in  the  form  of  the  tracing  may 
be  obtained  by  modifying  the  distance.  In  fact,  when  this 
distance  is  increased,  the  waves  of  sound  which  result  from 
composite  sounds  react  on  the  membrane  at  different  moments 
of  their  emission.  For  example,  if  the  composite  sound  is 
formed  of  six  harmonics,  the  displacement  of  the  source  of 
vibration  from  the  first  harmonic  by  one-quarter  the  length  of 
a  wave  will  respectively  remove  the  second,  third,  fourth,  fifth, 
and  sixth  harmonics  -J,  f,  1, 1^,  1-J  the  length  of  a  wave,  and 
consequently  the  outline  resulting  from  the  combination  of 
waves  will  no  longer  be  the  same  as  it  was  before  the  displace- 
ment of  the  source  of  sound,  although  the  perception  of  the 
sounds  remains  the  same  in  both  cases.  This  principle  is  clear- 
ly demonstrated  by  Koenig's  instrument,  by  lengthening  and 
shortening  an  extensible  tube,  inserted  between  the  resonator 
and  the  vibrating  membrane,  which  is  placed  close  to  the 
flame ;  and  this  explains  the  disagreement  of  physicists  as  to 
the  composition  of  vocal  sounds  which  they  have  analyzed  by 
means  of  the  singing  flames. 

Mr.  Mayer  adds  that  these  facts  further  show  that  we  cannot 
hope  to  read  the  impressions  and  tracings  of  the  phonograph, 
which  not  only  vary  with  the  nature  of  the  voice,  but  also  with 
the  different  moments  at  which  the  harmonics  of  the  voice  are 
emitted,  and  with  the  relative  differences  in  the  intensities  of 
these  harmonics. 

Notwithstanding  this  assertion,  we  reproduce  (Fig.  72)  an 
extremely  curious  tracing  sent  to  us  by  Mr.  Blake,  which  repre- 
sents the  vibrations  produced  by  the  words  "  Brown,  Univer- 
sity :  how  do  you  do  ?"  They  were  photographed  by  means 
of  an  index  fastened  to  a  vibrating  disk  on  which  a  ray  of 
light  was  thrown.  The  word  "  how  "  is  particularly  remark- 
able for  the  combined  forms  of  the  inflections  of  the  vibra- 
tions. 


254 


THE    PHONOGRAPH. 


Recent  experiments  seem  to  show  that  the  more  the  vibrat- 
ing membrane  of  the  phonograph  resembles  the  human  ear  in 
its  construction,  the  better  it  repeats  and  registers  the  sound 


FIG.  72. 

vibrations :  it  should  be  stretched,  as  far  as  possible,  in  the 
same  way  as  the  tympanum  is  stretched  by  the  hammer  of  the 
ear,  and  moreover  it  should  have  the  same  form,  since  the 
vibrations  of  air  are  in  this  case  much  more  effective. 

Mr.  Edison  considers  that  the  size  of  the  opening  of  the 
mouth-piece  has  considerable  influence  on  the  distinct  articula- 
tion of  speech.  When  the  sounds  are  pronounced  before  the 
whole  surface  of  the  diaphragm,  some  hissing  sounds  are  lost. 
They  are,  on  the  contrary,  intensified  when  these  sounds  reach 
the  diaphragm  through  a  narrow  orifice  with  sharp  rims.  If 
the  opening  is  toothed  on  its  flattened  rims,  the  hissing  con- 
sonants are  delivered  more  clearly.  Speech  is  reproduced 
more  perfectly  when  the  mouth-piece  has  a  covering  of  some 


USES    OF   THE   PHONOGRAPH.  255 

thickness,  so  arranged  as  to  deaden  the  sounds  arising  from 
the  friction  of  the  tracing-point  on  the  tin. 

Mr.  Hardy  has  rendered  the  registration  of  phonographic 
tracings  more  easy  by  adding  a  small  ebonite  tube,  resembling 
the  mouth-piece  of  a  wind  instrument,  to  the  mouth-piece  of 
the  phonograph. 

USES  OF  THE  PHONOGRAPH,  AND  ITS  FUTURE. 

Mr.  Edison  has  lately  published  in  the  North  American  Re- 
view of  May  to  June,  1878,  an  article  on  the  future  of  the 
phonograph,  in  which  he  himself  discusses  the  different  ap- 
plications which  may  be  made  of  this  instrument.  Without 
sharing  all  his  anticipations,  which  appear  to  us  to  be  very 
premature,  we  think  that  some  extracts  from  his  paper  may  be 
interesting. 

"  In  order  to  furnish  a  basis  on  which  the  reader  may  take 
his  stand  ...  a  few  categorical  questions  and  answers  are  given 
upon  the  essential  features  of  the  principle  involved. 

"1.  Is  a  vibrating  plate  or  disk  capable  of  receiving  a  com- 
plex motion  which  shall  correctly  represent  the  peculiar  property 
of  each  and  all  the  multifarious  vocal  and  other  sound  waves  ? 

"  The  telephone  answers  affirmatively. 

"  2.  Can  such  complex  movement  be  transmitted  from  such 
plate  by  means  of  a  single  embossing-point  attached  thereto, 
to  effect  a  record  upon  a  plastic  material,  by  indentation,  with 
such  fidelity  as  to  give  to  such  indentations  the  same  varied 
and  complex  form  ?  And  if  so,  will  this  embossing-point,  upon 
being  passed  over  the  record  thus  made,  follow  it  with  such 
fidelity  as  to  transmit  to  the  disk  the  same  variety  of  move- 
ment, and  thus  effect  a  restoration  or  reproduction  of  the  vocal 
or  other  sound  waves,  without  loss  of  any  property  essential  to 
producing  on  the  ear  the  same  sensation  as  if  coming  direct 
from  the  original  source  ? 

"The  answer  to  this  may  be  summed  up  in  a  statement  of 


256  THE    PHONOGRAPH. 

the  fact  that  .  .  .  the  writer  has  at  various  times  during  the 
past  weeks  reproduced  these  waves  with  such  degree  of  accura- 
cy in  each  and  every  detail  as  to  enable  his  assistants  to  read, 
without  the  loss  of  a  word,  one  or  more  columns  of  a  news- 
paper article  unfamiliar  to  them,  and  which  were  spoken  into 
the  apparatus  when  they  were  not  present.  The  only  percep- 
tible loss  was  found  to  be  in  the  quality  of  the  utterance,  a 
non-essential  in  the  practical  application  of  the  instrument. 
Indeed,  the  articulation  of  some  individuals  has  been  percepti- 
bly improved  by  passage  through  the  phonograph,  the  original 
utterance  being  mutilated  by  some  imperfection  of  lip  and 
mouth  formation,  and  these  mutilations  corrected  or  eliminated 
by  the  mechanism  of  the  phonograph.1 

"  3.  Can  a  record  be  removed  from  the  apparatus  on  which 
it  was  made,  and  replaced  upon  a  second  without  mutilation  or 
loss  of  effective  power  to  vibrate  the  second  plate  ? 

"  This  is  a  mere  mechanical  detail,  presenting  no  greater  ob- 
stacle than  having  proper  regard  for  the  perfect  interchange- 
ableness  of  the  various  working  parts  of  the  apparatus — not  so 
nice  a  problem  as  the  manufacture  of  the  American  watch. 

"4.  What  as  to  the  facility  of  placing  and  removing  the 
second  sheet,  and  as  to  its  transportation  by  mail  ? 

"  But  ten  or  fifteen  seconds  suffice  for  such  placing  or  re- 
moving. A  special  envelope  will  probably  be  required,  the 
weight  and  form  of  which,  however,  will  but  slightly  increase 
the  cost  of  postage. 

"  5.  What  as  to  durability  ? 

"Repeated  experiments  have  proved  that  the  indentations 
possess  wonderful  enduring  power,  even  when  the  reproduction 
has  been  effected  by  the  comparatively  rigid  plate  used  for 


1  We  confess  that  we  find  it  difficult  to  believe  in  this  property  of  the 
phonograph,  from  which  we  have  only  heard  the  harsh  and  unpleasant 
voice  of  Punch. 


257 

their  production.  It  is  proposed,  however,  to  use  a  more 
flexible  plate  for  reproducing,  which,  with  a  perfectly  smooth 
stone  point — diamond  or  sapphire — will  render  the  record  ca- 
pable of  from  fifty  to  one  hundred  repetitions,  enough  for  all 
practical  purposes. 

"  6.  What  as  to  duplication  of  a  record  and  its  permanence  ? 

"  Many  experiments  have  been  made,  with  more  or  less  suc- 
cess, in  the  effort  to  obtain  electrotypes  of  a  record,  and  the 
writer  is  informed  that  it  has  very  recently  been  successfully 
accomplished.  He  can  certainly  see  no  great  practical  obstacle 
in  the  way.  This,  of  course,  permits  of  an  indefinite  multipli- 
cation of  a  record,  and  its  preservation  for  all  time. 

"  7.  What  is  the  requisite  force  of  wave  impinging  upon  the 
diaphragm,  and  the  proximity  of  the  mouth  to  the  diaphragm, 
to  effect  a  record  ? 

"  These  depend  in  great  measure  upon  the  volume  of  sound 
desired  in  the  reproduction.  If  the  reproduction  is  to  be  made 
audible  to  an  assembly,  considerable  force  is  requisite  in  the 
original  utterance ;  if  for  the  individual  ear,  only  the  ordinary 
conversational  tone  (even  a  whisper  has  been  reproduced).  In 
both  cases  the  original  utterances  are  delivered  directly  in  the 
mouth-piece  of  the  instrument.  An  audible  reproduction  may, 
however,  be  had  by  speaking  at  the  instrument  from  a  distance 
of  from  two  to  three  feet  in  a  loud  tone.  The  application  of  a 
flaring  tube  or  funnel  to  collect  the  sound  waves,  and  the  con- 
struction of  an  especially  delicate  diaphragm  and  embossing- 
point,  etc.,  are  the  simple  means  which  suggest  themselves  to 
effect  this.  .  .  . 

"  The  foregoing  presentment  of  the  stage  of  development 
reached  by  the  several  essential  features  of  the  phonograph 
demonstrates  the  follow  ing  faits  accomplis  : 

"  1.  The  captivity  of  all  manner  of  sound  waves,  hitherto 
designated  as  *  fugitive,'  and  their  retention. 

"  2.  Their  reproduction  with  all  their  original  characteristics, 


258  THE    PHONOGRAPH. 

without  the  presence  or  consent  of  the  original  source,  and  after 
the  lapse  of  any  period  of  time. 

"  3.  The  transmission  of  such  captive  sounds  through  the 
ordinary  channels  of  commercial  intercourse  and  trade  in  a 
material  form,  for  purposes  of  communication. 

"  4.  Indefinite  multiplication  and  preservation  of  such  sounds, 
without  regard  to  the  existence  or  non-existence  of  the  original 
source. 

"  5.  The  captivation  of  sounds,  with  or  without  the  knowl- 
edge or  consent  of  the  source  of  their  origin.  .  .  . 

"The  apparatus  now  being  perfected  in  mechanical  details 
will  be  the  standard  phonograph,  and  may  be  used  for  all  pur- 
poses except  such  as  require  special  form  of  matrix,  such  as 
toys,  clocks,  etc.,  for  an  indefinite  repetition  of  the  same  thing. 
The  main  utility  of  the  phonograph  being,  however,  for  the 
purposes  of  letter- writing  and  other  forms  of  dictation,  the 
design  is  made  with  a  view  to  its  utility  for  that  purpose. 

"  The  general  principles  of  construction  are,  a  flat  plate  or 
disk,  with  spiral  groove  on  the  face,  worked  by  clock-work  un- 
derneath the  plate ;  the  grooves  are  cut  very  closely  together, 
so  as  to  give  a  great  total  length  to  each  length  of  surface — 
a  close  calculation  gives  as  the  capacity  of  each  sheet  of  foil 
nearly  40,000  words.  The  sheets  being  but  ten  inches  square, 
the  cost  is  so  trifling  that  but  a  hundred  words  might  be  put  on 
a  single  sheet  economically.  .  .  . 

"The  practical  application  of  this  form  of  phonograph  is 
very  simple.  A  sheet  of  foil  is  placed  in  the  phonograph,  the 
clock-work  set  in  motion,  and  the  matter  dictated  into  the 
mouth-piece  without  other  effort  than  when  dictating  to  a  ste- 
nographer. It  is  then  removed,  placed  in  suitable  form  of  en- 
velope, and  sent  through  the  ordinary  channels  to  the  corre- 
spondent for  whom  it  is  designed.  He,  placing  it  upon  his 
phonograph,  starts  his  clock-work,  and  listens  to  what  his  cor- 
respondent has  to  say." 


LAMBEIGOT'S  SYSTEM.  259 

Since  this  paper  by  Mr.  Edison  appeared,  in  June,  1878,  he 
has  applied  the  phonograph  to  several  other  purposes,  among 
which  we  may  mention  that  of  registering  the  force  of  sounds 
on  railways,  and  especially  on  the  Metropolitan  Atmospheric 
Railway  in  New  York.  The  instrument  which  he  has  made 
for  this  purpose  resembles  that  by  Mr.  Leo  Scott,  and  bears 
the  same  name.  It  is  described  and  represented  in  the  Daily 
Graphic  of  July  19th,  1878,  as  well  as  the  aerophone,  the  mega- 
phone, and  the  microtasimeter,  which  is  adapted  for  astronom- 
ical observations.  We  should  exceed  the  limits  laid  down  for 
this  volume,  if  we  were  to  give  a  more  detailed  account  of  these 
inventions. 

M.  Lambrigot,  one  of  the  officials  on  the  telegraphic  lines  in 
France,  and  the  author  of  various  improvements  in  the  Caselli 
telegraph,  has  shown  me  a  phonographic  system  of  his  own  in- 
vention in  which  it  is  reduced  to  its  simplest  form.  He  sent 
me  the  following  description  of  his  system: 

"  The  instrument  consists  of  a  wooden  slab  placed  vertically 
on  a  stand  and  firmly  fixed  upon  it.  There  is  a  round  open- 
ing in  the  middle  of  the  slab,  covered  by  a  tightly  stretched 
sheet  of  parchment  bearing  a  steel  knife,  which,  like  the  trac- 
ing-point of  the  phonograph,  is  intended  to  trace  the  vibra- 
tions. A  solid  block  rises  from  the  stand  to  the  middle  of  the 
slab,  and  supports  a  slide  on  which  a  runner  can  move  in  front 
of  the  slab.  There  is  a  strip  of  glass  on  this  runner,  of  which 
one  side  is  covered  with  stearine.  When  the  runner  is  moved 
to  and  fro,  the  stearine  comes  in  contact  with  the  knife  and 
takes  the  mould  of  its  form,  which  is  curved  throughout. 

"A  sound  places  the  sheet  of  parchment  in  vibration,  and 
imparts  its  movement  to  the  knife,  which  traces  various  lines 
on  the  surface  of  the  stearine. 

"  The  reproduction  thus  obtained  on  the  strip  of  glass  is 
subjected  to  the  ordinary  processes  of  metallization.  By  gal- 
vanism a  deposit  of  copper  is  obtained  which  reproduces  the 


260  THE    PHONOGRAPH. 

lines  in  an  inverse  way.  In  order  to  make  the  metallic  plate 
speak,  it  is  necessary  to  pass  a  point  of  ivory,  wood,  or  horn 
lightly  over  the  signs,  and,  by  moving  it  more  or  less  quickly, 
the  different  tones  can  be  heard,  just  as  they  were  spoken. 

"Since  copper  is  relatively  harder  than  lead,  the  copper 
plate  on  which  the  vibrations  are  traced  will  afford  an  unlim- 
ited number  of  reproductions.  To  obtain  this  result,  a  lead 
wire  must  be  applied  to  the  plate,  and  due  pressure  must  be 
exerted  on  it.  The  wire  is  flattened  and  takes  the  impression 
of  all  the  traces,  which  then  appear  in  relief.  If  the  edge  of  a 
card  is  passed  through  this  impressed  tracing,  the  same  sounds 
are  produced  as  those  which  are  obtained  from  the  copper 
plate." 

M.  Lambrigot  suggests  that  the  speaking -plates  might  be 
useful  in  many  ways  :  for  example,  they  might  make  it  easy  to 
learn  the  correct  pronunciation  of  foreign  languages,  since  a 
sufficient  number  might  be  collected  to  make  a  sort  of  vocabu- 
lary which  would  give  the  accent  of  the  words  most  in  use  in 
a  given  language. 

By  this  simple  process  M.  Lambrigot  has  been  able  to  ob- 
tain a  strong  impression,  within  a  copper  groove,  of  the  vibra- 
tions caused  by  the  voice,  and  they  are  so  distinctly  engraved 
that  whole  sentences  may  be  heard,  if  they  are  retraced  by  the 
sharpened  point  of  a  match.  It  is  true  that  the  reproduction 
is  imperfect,  and  that  those  words  are  only  to  be  distinguished 
which  were  previously  known  ;  but  it  is  possible  that  better 
results  will  be  obtained  from  improvements  in  the  system,  and 
at  any  rate  the  distinct  impression  of  the  vibrations  of  the 
voice  on  a  hard  metal  is  a  really  interesting  discovery. 

I  have  made  one  somewhat  important  observation  in  the 
working  of  the  phonograph,  namely,  that  if  speech  is  registered 
on  the  instrument  in  a  very  hot  room,  and  it  is  then  carried  to 
a  colder  room,  the  reproduction  of  speech  is  imperfect  in  pro- 
portion to  the  difference  of  temperature.  This  is  probably 


SPEAKING-MACHINE.  261 

owing  to  considerable  modifications  in  the  elasticity  of  the 
caoutchouc  pad  which  is  inserted  between  the  tracing -point 
and  the  vibrating  disk :  perhaps  differences  of  expansion  in 
the  tin-foil  have  also  some  effect. 

FABER'S  AMERICAN  SPEAKIXG-MACHIXE. 

About  two  years  ago  the  newspapers  announced  with  some 
pomp  that  a  speaking -machine  had  reached  Paris,  which  far 
surpassed  Vaucanson's  duck,  and  which  would  attract  general 
attention.  Unfortunately  the  invention  was  not,  in  the  first 
instance,  brought  forward  with  any  scientific  authority,  and 
was  soon  relegated  to  take  a  place  among  the  curiosities  ex- 
hibited by  conjurors.  In  a  country  so  essentially  critical  and 
sceptical  as  France,  there  are  always  those  who  profess  incre- 
dulity, and  who  will  even  resist  evidence,  and  it  was  asserted 
that  the  machine  only  spoke  because  its  exhibitor  was  an  able 
ventriloquist.  This  is  an  old  assertion  which  has  lately  been 
made  with  reference  to  the  phonograph.  Some  scientific  pa- 
pers echoed  the  absurdity,  and  the  speaking-machine  was  so 
discredited  that  it  is  now  unnoticed,  although  it  is  a  most  in- 
genious and  interesting  conception.  When  will  our  country 
be  cured  of  the  error  of  denying  everything  without  due  ex- 
amination ? 

Since  we  ourselves  only  judge  of  things  after  having  serious- 
ly considered  them,  we  think  it  just  to  vindicate  the  truth  as 
to  Mr.  Faber's  machine,  and  this  can  only  be  done  by  an  exact 
description  of  it. 

As  I  said  in  the  last  chapter,  there  is  a  great  difference  be- 
tween the  production  and  the  reproduction  of  a  sound,  and  a 
machine  like  the  phonograph,  adapted  for  the  reproduction  of 
sound,  may  differ  essentially  from  a  machine  which  really 
speaks.  In  fact,  the  reproduction  even  of  articulate  sounds 
may  be  very  simple,  as  soon  as  we  possess  the  means  of  stereo- 
typing the  vibrations  of  air  necessary  to  transmit  these  sounds ; 


262  THE    PHONOGRAPH. 

but  in  order  to  produce  them,  and  especially  to  emit  the  com- 
plex vibrations  which  constitute  speech,  it  is  necessary  to  set 
in  motion  a  number  of  special  organs,  fulfilling  more  or  less 
exactly  the  functions  of  the  larynx,  the  mouth,  the  tongue,  the 
lips,  and  even  the  nose.  For  this  reason,  a  speaking-machine 
is  necessarily  very  complicated,  and  this  is  precisely  the  case 
with  the  machine  we  are  now  considering.  Such  a  machine  is 
not  now  made  for  the  first  time,  and  the  Academy  has  lately 
been  reminded  of  a  speaking-head  which  was  in  the  possession 
of  the  philosopher  Albertus  Magnus  in  the  thirteenth  century, 
and  which  was  destroyed  by  St.  Thomas  Aquinas  as  a  diaboli- 
cal invention. 

Mr.  Faber's  speaking-machine  was  exhibited  two  years  ago 
at  the  Grand  Hotel,  and  may  now  be  seen  in  the  room  ad- 
joining M.  Robert  Houdin's  theatre,  the  same  room  in  which 
Mr.  Giffard  exhibited  the  telephone.  It  consists  of  three  dis- 
tinct parts :  1st,  of  a  large  bellows  worked  by  a  pedal,  which 
produces  the  currents  of  air  necessary  for  the  production  of 
sounds,  and  to  some  extent  acts  as  the  lungs ;  2d,  a  vocal  in- 
strument, consisting  of  a  larynx  accompanied  by  diaphragms 
of  various  forms  to  modify  the  sounds,  of  a  mouth  with  caout- 
chouc lips  and  tongue,  and  of  a  tube  with  an  outlet  somewhat 
resembling  the  nasal  cavities ;  3d,  of  a  system  of  jointed  levers 
and  of  pedals,  terminating  in  keys  like  those  of  a  piano. 

The  most  interesting  part  of  the  machinery,  of  which  we 
represent  the  principle,  Fig.  73,  is  the  vocal  apparatus,  which 
involved  the  severest  study  of  physics  in  order  to  succeed  in 
the  production  of  articulate  sounds.  It  consists,  first,  of  a 
rather  thick  caoutchouc  tube,  within  which  there  is  a  kind  of 
whistle,  L,  as  in  a  clarionet.  The  whistle  consists  of  a  small 
caoutchouc  cylinder  with  a  longitudinal  slit,  and  before  this 
is  placed  a  very  thin  ivory  plate  lined  with  caoutchouc.  This 
plate  is  fixed  at  one  end  to  the  cylinder,  and  deviates  slightly 
from  it  at  its  free  end,  so  as  to  permit  the  current  of  air  pro- 


SPEAKING-MACUIXE. 


263 


jected  from  the  bellows,  S,  to  penetrate  between  the  two  parts, 
and  to  cause  the  vibrations  in  the  ivory  plate  necessary  for  the 
production  of  a  sound.  The  extremity  of  the  caoutchouc  cyl- 
inder is  closed  on  this  side,  and  is  fitted  to  an  iron  rod,  t,  which 
comes  out  of  the  pipe,  and  is  connected  with  a  system  of  bars, 
corresponding  to  the  key-board  of  a  piano,  by  which  the  force 
of  sounds  can  be  regulated.  This  force  depends  on  the  width 
of  the  opening  between  the  tongue  and  the  cylinder. 

' 


V 


/ 


FIG.  73. 


The  whistle,  which  plays  the  part  of  the  larynx,  is  neces- 
sarily placed  opposite  the  opening  of  the  bellows,  and  a  sort  of 
tourniquet,  M,  is  fastened  to  the  opening  itself,  which  is  able  to 
move  on  certain  conditions,  so  that  it  may  produce  the  rolling 
sound  of  r.  This  is  done  by  fastening  before  the  opening  a 
diaphragm  in  which  there  is  a  somewhat  wide  and  long  slit, 
and  this  slit  can  be  almost  closed  by  a  little  bar  of  the  same 
size,  M,  revolving  on  a  transverse  axis  which  supports  it  by  its 
centre.  In  its  normal  condition,  this  little  bar  is  kept  in  a 
slanting  position  by  cords  attached  to  the  key-board,  and  the 


264  THE   PHONOGRAPH. 

air  ejected  by  the  bellows  readily  traverses  the  slit  in  order  to 
reach  the  larynx ;  but  two  dampers  are  fastened  to  the  rods 
which  transmit  movement,  with  which  the  cords  just  mention- 
ed are  also  connected.  On  lowering  the  notes  of  the  key-board, 
the  passage  of  air  is  contracted,  and  the  little  plate  begins  to 
oscillate  and  to  press  against  a  band  of  leather,  producing  by 
its  vibration  an  action  similar  to  that  produced  by  the  cricket. 
This  little  tourniquet  only  begins  to  act  when  the  dampers  are 
lowered  by  a  pedal  worked  by  the  hand ;  and  this  is  also  the 
case  with  the  iron  rod  t,  which  modifies  the  acuteness  of  the 
sounds  passing  through  the  larynx.1 

Below  the  larynx  tube,  which  is  only  five  centimetres  in 
length,  there  is  another  pipe,  G,  also  of  caoutchouc,  which  ter- 
minates in  a  spherical  cavity  connected  with  the  outer  air  by 
a  caoutchouc  tube,  I,  slightly  raised,  and  closed  by  a  valve,  of 
which  the  movements  are  regulated  by  a  pedal  worked  by  the 
key-board.  When  the  valve  is  open,  the  sounds  emitted  through 
the  larynx  are  somewhat  nasal.2  The  larynx  communicates  with 
the  mouth  through  a  square  funnel-shaped  pipe  to  which  six 
metallic  diaphragms,  D,  are  fastened ;  the  diaphragms  are  placed 
in  a  vertical  position  behind  each  other,  and  have  indentations 
on  their  lower  end,  which  are  intended  to  dimmish  more  or 
less  the  orifice  for  the  current  of  air,  and  to  impede  its  passage 
with  greater  or  less  force.  The  diaphragms,  which  we  repre- 

1  The  action  of  this  pedal  is  effected  by  two  little  rockers,  so  connected 
that  the  upper  damper  is  lowered  a  little  before  the  lower  damper  is  raised 
— a  condition  necessary  to  produce  the  quivering  motion  of  the  plate  which 
furnishes  the  rolling  r. 

a  The  arrangement  of  this  part  of  the  instrument  is  remarkable  in  this 
particular,  that  in  the  case  of  certain  letters  the  air  is  ejected  with  more 
or  less  force  through  the  pipe  I,  while  in  the  case  of  other  letters  the  air 
is  drawn  into  the  same  tube.  Since  I  was  unable  to  see  the  internal  ar- 
rangement of  these  cavities,  I  can  only  give  an  imperfect  account  of  the 
mechanism  at  work. 


SPEAKING-MACHINE. 


2G5 


sent  separately,  Fig.  74,  are  connected  with  the  key-board  by 
jointed  iron  rods,  £,  and,  for  the  emission  of  most  articulate 
sounds,  several  of  the  diaphragms  are  moved  at  the  same  mo- 
ment and  at  different  heights.  We  shall  return  to  this  subject. 


FIG.  74. 


The  mouth  consists  of  a  caoutchouc  cavity,  O,  somewhat 
resembling  the  human  mouth,  and  forming  a  continuation  to 
the  channel  we  have  just  described.  The  tongue,  C,  likewise 
modelled  on  the  human  tongue,  is  placed  within  the  mouth, 
and  connected  with  two  jointed  rods,  t,  t,  fastened  to  its  two 
opposite  ends,  so  as  to  enable  the  tongue  to  raise  its  tip,  or 
touch  the  palate,  in  obedience  to  the  notes  of  the  key-board. 
The  lower  caoutchouc  lip,  A,  can  also  be  more  or  less  closed, 
according  to  the  action  of  the  key-board  on  its  special  rod. 
Finally,  a  circular  metallic  piece,  E,  following  the  shape  of  the 
mouth,  is  placed  above  the  upper  lip,  with  a  small  opening  in 
it  to  admit  of  the  pronunciation  of  the  letter/. 

The  key -board  has  fourteen  notes,  of  different  lengths,  pro- 
ducing the  following  letters  when  lowered :  a,  o,  w, i,  e,  /,  r,  v,f, 
s,  ck,  6,  d,  g.  The  longest  corresponds  to  g,  and  the  shortest  to 

12 


266  THE   PHONOGRAPH. 

a.  There  are  two  pedals  below  the  g  note  and  those  of  b  and 
d,  corresponding  with  the  opening  of  the  tube  which  produces 
nasal  sounds,  and  to  the  rod  which  regulates  the  opening  of 
the  larynx,  and  this  makes  it  possible  to  obtain  p,  t,  and  k  from 
the  notes  b,  d,  g.  The  mechanical  effects  produced  by  lower- 
ing the  different  notes  in  succession  are  as  follows : 

1.  The  a  note  moves  the  first  five  diaphragms. 

2.  o  also  moves  these  five  diaphragms,  but  varies  the  pitch, 
and  closes  the  mouth  a  little. 

3.  u  does  the  same,  only  farther  closing  the  mouth. 

4.  t  moves  a  single  diaphragm,  raises  the  tip  of  the  tongue, 
and  opens  the  mouth  more  widely. 

5.  e  moves  six  diaphragms,  throw's  the  tongue  farther  back, 
and  opens  the  mouth  still  more. 

6.  I  moves  five  diaphragms,  sends  the  tongue  against  the 
palate,  and  farther  opens  the  mouth. 

7.  r  moves  six  diaphragms  and  the  tourniquet,  lowers  the 
tongue,  and  somewhat  closes  the  mouth. 

8.  v  moves  five  diaphragms,  almost  closes  the  mouth,  and 
keeps  the  tongue  down. 

9.  /  lowers  the  circular  appendix  of  the  upper  lip,  and  almost 
entirely  closes  the  mouth. 

10.  s  moves  three  diaphragms,  half  closes  the  mouth,  and 
half  raises  the  tongue. 

11.  ch  moves  three  diaphragms,  keeps  the  mouth  half  closed, 
and  farther  lowers  the  tongue. 

,  12.  b  moves  five  diaphragms,  closes  the  mouth,  and  keeps 
the  tongue  completely  down. 

13.  d  moves  six  diaphragms,  keeps  the  mouth  three  parts 
closed,  and  raises  the  tongue  a  little. 

14.  g  moves  five  diaphragms,  keeps  the  mouth  three  parts 
closed,  and  the  tongue  completely  down. 

m  is  produced  by  lowering  note  b,  and  opening  the  valve  of 
the  pipe  which  gives  nasal  sounds. 


SPEAKING-MACHINE.  267 

n  is  obtained  by  lowering  note  d,  and  opening  the  same 
valve. 

h  is  obtained  from  note  s  by  lowering  the  pedal  which  acts 
upon  the  larynx,  and  half  closing  it. 

Since  the  other  letters  of  the  alphabet  are  compound  sounds, 
they  can  be  produced  by  combinations  of  the  preceding 
letters. 

Although  the  words  pronounced  by  this  machine  are  dis- 
tinct, they  are  spoken  in  a  uniform,  drawling  tone,  which 
might,  I  should  have  thought,  have  excluded  the  idea  of  im- 
position. Some  of  them  are  indeed  far  from  distinct,  yet  the 
results  are  not  less  remarkable;  and  when  we  consider  the 
amount  of  study  and  experience  which  must  have  been  applied 
to  the  combination  of  all  these  arrangements;  it  seems  surpris- 
ing that  physicists  have  not  given  more  attention  to  such  an 
interesting  machine. 

As  for  the  mechanical  execution,  it  is  impossible  to  admire 
too  highly  the  simple  and  ingenious  manner  in  which  all  the 
complicated  movements  of  the  different  vocal  organs  have  been 
connected  with  the  key  -  board,  of  which  the  mechanism  has 
been  so  calculated  as  only  to  produce  the  precise  action  of  the 
organ  which  is  required  for  any  given  effect.  For  this  pur- 
pose, the  notes  of  the  key-board  regularly  increase  in  length, 
so  as  to  produce  at  a  single  touch  different  mechanical  effects 
on  the  rods  which  act  upon  the  mechanism ;  and  since  most 
of  the  notes  are  required  to  react  simultaneously  on  the  whole 
mechanism,  the  rods  which  transmit  the  movement  are  fastened 
to  a  series  of  jointed  levers  which  cross  the  notes  of  the  key- 
board at  right  angles.  Pegs  of  different  length  are  fastened 
to  the  notes  at  this  junction,  so  as  to  produce  the  simultaneous 
action  of  the  different  organs  of  the  machine. 

The  public  will  believe  that  the  assertions  of  ventriloquism 
are  unfounded  when  I  add  that  I  myself  have  made  the 
machine  speak. 


APPENDIX. 


The  Ferrodon  System  of  Telephonic  Alarum. — Captain  Perrodou,  of 
the  French  Artillery,  has  lately  improved  the  system  invented  by 
MM.  Dntertre  and  Gouault,  by  a  self-acting  call.  For  this  purpose 
he  has  fastened  a  spring  contact  before  the  diaphragm,  combined 
with  the  diaphragm  and  the  electro-magnetic  system  so  as  to  form 
a  vibrator.  The  vibrations  thus  produced  are  strong  enough  to 
resound  in  an  ordinary  telephone,  so  as  to  make  the  call  audible  in 
spite  of  external  noises. 

The  system  has  been  arranged  in  different  ways.  In  one  ar- 
rangement, a  small  plate  of  tin-foil  is  glued  to  the  outer  surface  of 
the  diaphragm,  and  the  end  of  the  telephone  coil-wire  is  connected, 
below  the  inner  surface  of  the  mouth-piece,  with  a  silver  wire  sol- 
dered to  a  spring  plate,  which  constitutes  the  contact  of  the  vibra- 
tor. This  spring  plate,  slightly  curved,  is  fixed  below  one  of  the 
binding-screws  of  the  telephone,  and  terminates  at  its  free  end  in  a 
regulating  screw  by  which  the  interval  between  the  contacts  can 
be  regulated,  and  the  instrument  can  be  arranged  as  a  telephonic 
organ.  To  do  this,  the  screw  can  be  withdrawn,  and  inserted  in  a 
nut  which  establishes  direct  connection  between  the  line  and  the 
telephone  coil.  It  is  easy  to  adapt  an  ordinary  telephone  to  this 
system. 

In  another  arrangement  M.  Courtot's  mirror  telephone  has  been 
employed,  and  a  sort  of  spring  pedal  is  inserted  in  the  wood  of  the 
mouth-piece,  which  terminates  in  a  bent  silver  wire,  supporting  an 
index  adapted  to  make  a  contact  with  a  square  plate  soldered  to 
the  diaphragm.  The  battery  is  placed  in  connection  with  the 
spring  of  the  pedal,  and  one  end  of  the  telephone  coil-wire  com- 
municates as  before  with  the  diaphragm.  When  a  call  is  to  be 
made,  the  pedal  must  be  pressed,  aud  the  battery  immediately 
communicates  with  the  silver  wire  which,  with  the  diaphragm, 
constitutes  the  vibrator,  and  an  electric  vibration  is  sent  through 
the  circuit,  and  produces  the  call.  For  receiving,  the  pedal  is  al- 


270  APPENDIX. 

lowed  to  revert  to  its  normal  position,  arid  the  index  of  the  pedal, 
touching  the  contact  in  connection  with  the  diaphragm,  establishes 
direct  communication  between  the  two  telephones,  while  breaking 
the  contact  of  the  silver  wire  with  the  diaphragm,  so  that  the  bat- 
tery cannot  act. 

It  appears  that  experiments  made  at  the  musketry  school  at 
Orleans  for  a  distance  of  370  miles  have  been  very  successful. 

M.  Varey's  Microphone  Speaker. — M.  Varey  has  recently  arranged 
a  successful  microphonic  speaker,  in  which  the  principle  of  the 
microphone  represented  in  Fig.  39  is  maintained.  The  system  of 
three  vertical  carbons  is  arranged  inside  a  sort  of  snuffbox,  of 
which  the  lid  is  made  of  a  thin  plate  of  mica,  horn,  or  ebonite. 
The  snuffbox  is  provided  with  two  hinged  arms,  so  that  it  may  be 
placed  in  the  most  convenient  position  for  speaking,  and  at  the 
same  time  the  sensitiveness  of  the  instrument  can  be  regulated.  A 
small  battery,  consisting  of  two  Gaiffe  cells  of  chloride  of  silver,  is 
placed  in  the  pedestal  on  which  the  instrument  stands,  and  sets 
the  microphone  at  work  without  further  trouble.  In  this  way  the 
speaker  can  be  used  like  an  ordinary  telephone,  and  is  not  affected 
by  vibrations  of  air.  Only  vibrations  of  sound  react  upon  it. 

Microphonic  Speaker  l)y  Fitch. — Mr.  Pope  states  that  this  speaker 
has  produced  excellent  results  in  America.  It  is  merely  Edison's 
carbon  telephone  reduced  to  its  simplest  form.  It  consists  of  a 
small  cylindrical  box,  which  has  a  mouth-piece  like  the  one  repre- 
sented in  Fig.  28.  The  box  contains  two  carbon  disks  of  the  same 
diameter  as  itself,  and  is  lined  with  a  kind  of  felt.  Metal  wires, 
inlaid  in  a  groove  scooped  on  the  circumference  of  the  carbons, 
place  them  in  communication  with  the  circuit  and  battery,  and 
transmission  takes  place  by  means  of  the  vibrations  of  the  upper 
carbon,  which  is  directly  influenced  by  the  voice  without  the  inter- 
vention of  any  diaphragm.  These  vibrations,  which  can  be  freely 
developed  in  consequence  of  the  elasticity  of  the  felt  pad  which 
supports  the  lower  carbon,  produce  on  the  surface  of  contact  of  the 
two  carbons  the  modifications  of  intensity  of  current  necessary  for 
the  reproduction  of  speech,  in  the  same  way  as  other  microphones. 

An  induction  coil  is  necessarily  employed  for  a  long  circuit,  and 
the  effects  of  induction  in  the  adjacent  wires  are  modified  by  two 
rheostats  introduced  into  the  circuit  at  its  two  extremities. 

Further  Remarks  on  the  Theory  of  the  Telephone. — Following  the  ex- 
ample of  a  certain  sceptic  in  the  Acaddmie  des  Sciences,  Colonel 
Navez  continues  to  maintain  the  theory  first  formed  as  to  the  mode 
in  which  the  telephone  acts,  in  spite  of  the  clearest  proofs  of  its  in- 


APPENDIX.  271 

sufficiency  ;  but  most  scientific  men  -who  consider  the  question  liave 
come  round  to  our  opinion,  and  admit  the  concurrence  of  several 
causes  in  the  reproduction  of  speech  by  this  remarkable  instru- 
ment. Mr.  Fleeming  Jenkiu  writes  to  this  effect  in  the  new  edi- 
tion of  a  treatise  on  electricity  and  magnetism. 

He  observes  that  a  singular  fact  has  been  discovered  by  several 
persons,  who  have  ascertained  that  not  merely  non-magnetic  and 
non-conducting  bodies  can  be  substituted  for  the  diaphragms  of 
receiving  telephones,  but  that  they  will  act  without  a  diaphragm 
at  all.  In  this  case  it  is  evident  that  we  have  to  do  with  the 
sounds  discovered  by  Page,  and  that  they  are  produced  by  the 
magnet  itself,  in  which  each  molecular  movement  constitutes  the 
source  of  the  sound  produced.  This  sound  becomes  articulate  as 
soon  as  its  increase  and  decrease  can  follow  the  increasing  or  de- 
creasing action  of  the  voice  which  produces  it  at  the  seuding-sta- 
tion.  It  is  certain  that  when  the  transmitted  currents  are  due  to 
the  action  of  the  Bell  diaphragm,  the  sounds  due  to  the  Page  effects 
ought  to  correspond  with  those  which  would  be  given  by  iron  dia- 
phragms adapted  to  the  receiving  instruments ;  so  that,  when  a 
telephone  has  an  iron  diaphragm,  there  are,  in  fact,  two  voices,  that 
of  the  diaphragm,  which  is  strong,  and  that  of  the  magnet,  which 
is  weak.  When  a  disk  of  wood  is  substituted  for  one  of  iron,  it 
acts  as  a  sounding-board  for  the  Page  effect,  and  when  the  disk  is 
of  metal,  induction  is  developed  by  the  magnetic  modifications,  and 
tends  to  produce  vibration,  thus  developing  a  third  source  of  sound, 
which  may  be  called  the  Ampere  effect.  Finally,  a  fourth  source 
of  sound  may  result  from  the  induced  effects  produced  in  the  wire 
itself  in  consequence  of  changes  in  the  intensity  of  current.  These 
sounds,  first  observed  by  M.  de  la  Rive,  have  since  been  studied  by 
Mr.  Fergusson,  of  Edinburgh  (vide  Telegraphic  Journal  of  November 
1st,  1878). 

Mr.  Fleeming  Jenkin's  opinion  only  differs  from  mine  in  his  as- 
cribing the  energy  of  sound  acquired  by  a  telephone  with  an  iron 
diaphragm  to  the  preponderance  of  sounds  in  the  latter,  whereas  I 
consider  it  to  be  chiefly  due  to  the  increase  of  energy  in  the  whole 
magnetic  system  produced  by  the  reaction  of  the  two  magnetic 
parts  on  each  other.  If  the  two  effects  could  be  taken  singly,  it 
is  probable  that  the  sounds  produced  by  each  of  them  separately 
would  be  similar,  since  in  magnetic  effects  the  reaction  and  action 
are  equal.  But  as  they  are  combined,  it  becomes  difficult  to  assign 
to  each  the  share  which  belongs  to  it  in  the  general  effect  observed. 
Besides,  it  is  quite  possible  that  the  sounds  of  the  diaphragm  may 


272  APPENDIX. 

appear  to  be  stronger  and  more  distinct,  because  it  is  nearer  to  the 
ear  than  the  magnet,  and  because  the  effects  of  magnetization  and 
demagnetization  are  then  more  easily  produced  in  consequence  of 
the  mass  of  the  magnetic  body  being  smaller. 

Mr.  Fleemiug  Jeukin  goes  on  to  say  that  the  question  of  the  dis- 
placement of  surface  in  the  diaphragm  and  magnet  is  very  com- 
plex, but  that  he  thinks  it  impossible  to  deny  the  existence  of  such 
displacement,  since  the  air  which  acts  as  the  vehicle  of  sound  be- 
tween the  ear  and  the  source  of  sound  is  placed  in  vibration ;  yet 
this  displacement  may  be  effected  quite  otherwise  than  by  flexion. 
Suppose  that  the  magnetic  molecules  of  these  bodies  are  drawn  to- 
gether by  magnetization,  which  tends  to  diminish  the  iutermolecu- 
lar  space  which  separates  them,  the  points  of  surface  of  the  sub- 
stance corresponding  to  these  intervals  will  be  elevated  in  a  man- 
ner equivalent  to  a  displacement  of  surface,  and  the  effect  of  this 
will  be  the  same  as  a  flexion  movement.  At  the  moment  of  de- 
magnetization a  depression  instead  of  an  elevation  will  take  place, 
and  the  vibratory  movements  will  thus  be  produced  without  any 
electro -magnetic  attraction,  and  it  is  precisely  these  vibrations 
which  Mr.  Fleeming  Jenkin  terms  molecular  vibrations.  He  evi- 
dently does  not  mean  that  such  attractions  cannot  take  place: 
they  may  react,  together  with  the  molecular  vibrations,  when  the 
electric  force  is  capable  of  producing  them.  He  adds  that  the  re- 
production of  sounds  by  a  condenser,  by  simple  coils,  and  by  a  car- 
bon microphone,  has  convinced  him  that  the  action  just  analyzed 
requires  generalization. 

We  have  recently  seen  an  article  by  Mr.  Hughes  in  the  Tele- 
graphic Journal,  Nov.  15th,  1878,  in  which,  to  our  surprise,  he  not 
only  opposes  all  the  theories  he  has  hitherto  held,  but  cites  experi- 
ments which  are  quite  inconclusive,  since  they  were  performed  un- 
der conditions  in  which  electro-magnetic  effects  must  necessarily 
be  displayed.  He  made  use  of  voltaic  currents  produced  by  a  bat- 
tery of  three  Daniell  cells.  In  order  to  estimate  the  transverse  ef- 
fects resulting  in  such  a  case  from  attraction,  the  experiments  ho 
mentions  are  wholly  unnecessary :  they  may  be  felt  with  the  hand. 
On  the  other  hand,  he  has  evidently  forgotten  that  the  currents 
employed  in  a  Bell  telephone  have  no  influence  on  a  very  sensitive 
galvanometer. 

M.  Pollard's  Microphone. — This  microphone,  which  has  been  ar- 
ranged in  several  ways,  essentially  consists  of  a  carbon  rod  kept  in 
a  horizontal  position  by  a  wire,  and  resting  on  two  other  vertical 
carbons.  The  upright  of  the  arm  which  holds  the  wire  can  revolve 


APPENDIX.  273 

together  with  this  arm,  and  is  thus  able  to  regulate  the  pressure  of 
the  horizontal  carbon  on  the  two  vertical  carbons.  It  appears  that 
this  instrument  is  extremely  sensitive,  and  that  the  regulation  ef- 
fected on  the  two  contacts  is  better  than  when  it  is  effected  on  one 
only.  It  is  fair  to  add  that  M.  Voisin  previously  sent  me  the  sketch 
of  a  somewhat  similar  arrangement. 

M.  Dutertre  has  also  made  use  of  such  an  arrangement  in  what 
he  calls  the  Dolmen  microphone.  Three  pieces  of  coke  in  the  form 
of  a  dolmen,  that  is,  two  uprights,  supporting  a  third  and  horizon- 
tal carbon,  are  placed  in  circuit.  M.  Gouault  has  informed  me  that 
speech  was  well  transmitted  by  this  instrument,  and  it  is,  like  that 
of  Mr.  Blyth,  which  succeeded  it,  of  wonderful  simplicity. 

This  microphone,  as  well  as  one  composed  of  two  pieces  of  lead- 
pencil  placed  in  a  watch-case,  and  connected  by  a  piece  of  money, 
were  exhibited  to  the  Industrial  Society  at  Rouen,  February  1st, 
1878,  of  which  an  account  was  published  in  the  Bulletin  of  that 
society. 

M.  Adc^s  Electrophone. — M.  Ader  has  recently  constructed  a  re- 
markable telephonic  instrument,  which  reproduces  speech  and  song 
in  a  quite  exceptional  and  simple  way.  It  consists  of  a  drum  fif- 
teen centimetres  in  diameter,  covered  with  parchment  at  one  end 
only.  Six  small  tin  armatures,  one  centimetre  in  length  and  two 
millimetres  in  width,  are  fixed  in  the  centre  of  the  parchment  in  a 
circle  six  centimetres  in  diameter.  Six  microscopic  electro-mag- 
nets, whose  distance  from  the  armatures  can  be  regulated  by  a 
screw,  are  placed  opposite  the  armatures  within  a  wooden  circle. 
The  magnets  are  horseshoe,  with  branches  twelve  millimetres  long 
and  four  millimetres  in  diameter,  including  the  coils,  and  the  mag- 
netic core  is  one  and  a  half  millimetre  thick.  They  are  all  in  con- 
nection, and  act  simultaneously  under  the  sole  influence  of  the  bat- 
tery current.  The  sender  is  the  same  as  that  of  M.  Ader  described 
before.  With  this  instrument  speech  may  be  heard  at  a  distance 
of  six  or  seven  yards,  and  songs  are  much  more  distinctly  heard 
than  in  the  singing  condenser.  Owing  to  the  simplicity  of  the  ar- 
rangement, the  instrument  is  not  costly. 

The  extraordinary  effects  of  this  telephone  are  due  to  the  small 
size  of  the  electro -magnets,  which,  as  we  believe,  produce  much 
more  rapid  magnetic  effects  than  those  of  larger  size.  M.  Ader  has 
also  made  a  small  ordinary  telephone  based  on  this  principle,  of 
which  the  sounds  are  much  stronger  than  in  others. 

Modification  of  Bell  Telephone. — Mr.  Gower  has  recently  made  a 
new  system  of  telephone  without  a  battery,  which  not  only  repro- 

12* 


274  APPENDIX. 

duces  speech  loudly  enough  to  he  heard  at  the  distance  of  eight  or 
nine  yards  from  the  instrument,  but  will  also  transmit  it  when  the 
speaker  is  at  a  moderate  distance  from  the  sending  instrument.  In 
this  latter  case,  indeed,  the  receiving  telephone  must  he  brought 
close  to  the  ear.  Although  this  double  problem  had  already  been 
solved  by  the  use  of  telephones  with  microphonic  senders,  the  re- 
sults furnished  by  the  instruments  in  question  are  still  more  curi- 
ous, since  they  are  obtained  without  batteries,  and  are  even  more 
distinct. 

In  this  new  system,  which  is  only  an  improvement  on  Bell's 
square  model,  the  horseshoe-magnet  is  of  a  peculiar  form,  which 
renders  it  more  powerful.  It  is  formed  of  a  kind  of  half-circle  of 
magnetized  steel,  with  its  two  ends  turned  back,  so  as  to  form  a 
diameter  of  the  circle,  only  this  diameter  is  divided  in  the  centre : 
so  that  the  two  poles  of  the  magnet  are  placed  one  before  the 
other,  as  in  Faraday's  electro-magnet.  The  poles  are  tipped  with 
iron,  terminating  in  front  in  two  thin  iron  plates,  on  which  are 
placed  the  electro-magnetic  coils,  which  are  oblong,  and  constitute 
the  magnetic  core.  The  diaphragm,  thicker  than  the  ordinary 
diaphragms,  is  of  tin,  and  is  fixed  firmly  to  the  edges  of  the  circular 
box  which  encloses  the  whole,  and  which  forms  a  kind  of  sounding- 
box.  The  box  is  made  of  copper,  and  the  diaphragm  is  so  firmly 
fastened  to  it  as  to  become  homogeneous  with  it,  and  to  give  out  a 
sound  when  the  box  is  touched,  which  is  not  the  case  in  ordinary 
telephones.  This  is  one  of  the  conditions  which  make  the  instru- 
ment a  better  conductor  of  sound.  The  magnetos  also  much  more 
powerful.  It  is  magnetized  by  a  current  from  a  powerful  Gramme 
machine,  which  acts  upon  it  for  almost  twenty  minutes.  The  in- 
strument has,  strictly  speaking,  no  mouth-piece :  the  lid  of  the  box 
which  supports  the  diaphragm,  and  is  separated  from  it  by  a  space 
of  two  millimetres,  has  merely  a  hole  bored  in  it  above  the  centre 
of  the  diaphragm,  and  into  this  hole  either  a  tin  trumpet,  fifty  cen- 
timetres in  length,  is  screwed,  when  the  instrument  is  required  to 
reproduce  or  transmit  speech  to  a  distance,  or  an  acoustic  tube 
when  it  is  to  be  used  like  an  ordinary  telephone.  The  remarkable 
part  of  the  system  is  that  the  instrument  can  itself  give  a  very 
loud  call  by  only  breathing  into  it  instead  of  speaking. 

For  this  purpose  a  small  oblong  opening  is  made  in  the  dia- 
phragm at  a  half  diameter  from  its  centre,  and  behind  this  the  reed  ' 
of  an  harmonium  is  applied  to  a  square  copper  plate  fixed  on  the 
diaphragm  itself.      On  using  the  bellows  the  expelled  air  passes 
through  this  little  hole,  and,  on  reaching  the  reed,  sets  it  in  vibra- 


APPENDIX.  275 

tion,  and  produces  a  sound  of  which  the  acuteuess  depends  on  the 
conditions  of  the  vibrating  plate.  This  addition  to  the  diaphragm 
in  no  way  alters  its  properties  in  the  reproduction  of  speech,  so 
that,  after  using  the  bellows,  conversation  may  begiu,  and  the  re- 
ceiving telephone  repeats  what  is  said  after  emitting  a  sound  some- 
what resembling  the  note  of  a  bugle.  The  instrument  is  then  pro- 
vided with  the  speaking-tube  of  which  we  have  spoken. 

Nothing  can  be  more  remarkable  than  this  power  of  listening  to 
conversation  while  seated  in  an  arm-chair  six  or  seven  yards  from 
the  instrument,  nor  is  it  necessary  to  move  in  order  to  reply.  The 
correspondent,  indeed,  must  be  close  to  the  acoustic  tube  in  order 
to  speak  and  listen,  and  he  must  speak  rather  loud  in  order  to  bo 
heard  at  any  distance  from  the  other  station.  But  the  listener 
receives  the  sounds  so  amplified  that  it  might  be  supposed  that  a 
giant  was  speaking,  and  conversation  held  in  a  low  tone  may  even 
be  distinguished.  These  results  are  really  extraordinary,  and  even 
to  those  familiar  with  such  effects  this  incessant  progress  is  sur- 
prising. 

These  results  may  be  ascribed  to  the  following  causes: 

1.  First,  that  the  conditions  of  the  magnet  are  better  than  those 
of  ordinary  instruments. 

2.  That  the  diaphragm  is  also  thicker,  larger,  and  better  stretched. 

3.  That  the  box  is  of  metal,  and  calculated  to  act  as  a  sounding- 
box. 

4.  The  speaking-trumpet  magnifies  the  sounds. 

5.  The  acoustic  tubes  concentrate  the  sound  waves  on  the  centre 
of  the  diaphragm. 


Note  on  some  fresh  Experiments  with  Telephones  without  any 
Diaphragm. 

In  a  paper  published  March  4th,  1878, 1  made  some  suggestions 
on  the  theory  of  the  sounds  produced  in  the  telephone,  and  on  the 
contradictory  assertions  of  physicists  as  to  the  transmission  of 
speech  by  ordinary  telephones  when  devoid  of  diaphragm.  These 
remarks  induced  M.  Ader  to  undertake  some  experiments  which 
not  only  demonstrate  the  truth  of  my  opinion,  but  bring  to  light 
some  fresh  facts  which  may  be  of  great  importance  to  acoustic 
science. 

M.  Ader  has  in  fact  not  only  succeeded  in  making  a  telephone 
without  a  diaphragm  speak,  but  he  has  made  it  speak  more  loudly 


27G  APPENDIX. 

aud  with  less  alteration  of  the  voice  than  we  find  to  be  the  case 
with  a  small  model  of  the  ordinary  telephone.  No  one,  therefore, 
can  now  maintain  that  the  sounds  produced  by  the  magnetic  cores 
are  so  faint  that  they  cannot  be  taken  into  account  among  the 
effects  produced,  and  that  it  is  at  any  rate  impossible  for  them  to 
reproduce  articulate  sounds. 

To  obtain  this  result,  M.  Ader  reduced  the  size  of  the  magnetic 
core  to  that  of  a  simple  iron  wire,  one  millimetre  in  diameter,  and 
ho  fastened  it  by  one  of  its  ends  to  a  small  wooden  board.  Under 
these  conditions,  it  was  enough  to  fasten  a  small  helix  of  fine  wire 
on  this  iron  wire,  aud  to  apply  the  board  to  the  ear  in  order  to  hear 
speech  distinctly,  with  the  aid  of  a  microphonic  speaker  actuated 
by  a  voltaic  current.  But  the  range  of  sound  was  considerably 
increased  if  a  mass  of  metal  was  applied  to  the  free  end  of  the  iron 
wire :  in  this  case  it  was  possible  to  hear  when  the  wooden  board 
was  removed  to  a  distance  of  ten  or  fifteen  centimetres  from  the 
ear. 

If  the  wire  is  in  contact  with  masses  of  metal  at  each  end,  the 
effect  is  further  increased ;  but  the  two  masses  must  not  be  in  me- 
tallic communication  with  each  other,  and  must  bo  to  some  extent 
insulated  by  a  more  or  less  elastic  medium.  If  the  metallic  masses 
are  soldered  to  the  wire,  the  effects  are  still  greater. 

M.  Ader  was  also  able  to  reproduce  speech  by  using  a  simple  coil 
without  a  magnetic  core,  but  in  this  case  the  spirals  must  be  open, 
aud  not  pressed  together.  If  they  are  steeped  in  gum,  no  sound  is 
heard,  but  speech  will  become  instantly  audible  if  a  wire  or  a  mag- 
netized needle  is  inserted  in  the  coil,  or  even  if  a  second  metallic 
helix  is  placed  in  the  circuit :  always  provided  that  one  of  the 
ends  of  these  magnetic  organs  rests  upon,  or  is  fastened  to,  the 
board  on  which  the  coil  is  fixed. 

M.  Ader  has  likewise  obtained  a  very  distinct  reproduction  of 
speech  at  a  distance  of  two  or  three  yards  from  the  instrument  by 
inserting  between  the  two  stretched  membranes  of  two  tambou- 
rines a  bent  wire  which  acts  as  a  spring  aud  passes  through  an 
electro-magnetic  coil.  Under  these  conditions,  magnetization  of 
the  wire  in  a  greater  or  less  degree  affects  its  elasticity  and  causes 
vibrations  which  are  magnified  by  the  membranes,  and  transmitted 
sounds  are  reproduced  with  intensity.  Unfortunately,  articulate 
speech  is  less  distinct  with  this  system  than  with  the  one  I  de- 
scribed before. 

M.  Ader  has  often  had  occasion  to  make  one  curious  remark, 
namely,  that  the  timbre  of  the  voice  and  its  high  or  low  key  varies 


APPENDIX.  277 

with  the  degree  of  tension  given  to  the  wire;  but  if  the  funda- 
mental note  of  the  wire  is  deadened  by  pressing  it  between  the 
fingers,  the  sounds  reproduced  then  become  dull  and  monotonous. 
They  are  also  somewhat  fainter. 

Signer  Carlo  Resio  has  also  observed  that  in  a  telephone  sender 
the  variations  of  intensity  in  the  current  correspond  with  the  vi- 
brations caused  by  speech,  and  these  are  reproduced  by  correspond- 
ing variations  in  a  liquid  column,  which  may  thus  act  as  a  tele- 
phone receiver,  and  consequently  may  reproduce  speech  without 
any  electro-magnetic  organ,  as  in  a  microphone-speaker.  Under 
these  conditions,  however,  a  layer  of  water  is  inserted  between  the 
platinum  electrodes  and  the  surrounding  air,  and  consequently  this 
liquid  layer  must  be  put  in  vibration  under  the  influence  of  vary- 
ing intensities  of  current. 

Mr.  Edison  has  also  now  made  a  practical  application  of  the 
chemical  telephone  we  have  mentioned  before.  The  trials  made 
with  it  have  been  very  satisfactory,  showing  that  sounds  transmit- 
ted in  this  way  can  be  heard  in  a  large  room. 


THE    END. 


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